A reloading system for a firearm

Abstract

A firearm comprises a reloading delay mechanism, wherein the reloading delay mechanism comprises a piston which is moveable within a pressure chamber between a first position and a second position. The piston is movable from the second position to the first position by pressure from combustion gasses communicated to the pressure chamber from a barrel of the firearm. The piston is configured to compress a compression element when moving from the second position to the first position, wherein a force exerted by the compressed compression element moves a bolt carrier group of the firearm during a reloading cycle, and wherein the reloading cycle does not begin before the first piston reaches the first position.

Description

[0001] A RELOADING SYSTEM FOR A FIREARM

[0002] FIELD OF INVENTION

[0003] This invention relates to an automatic bolt reloading system for a firearm, in which the reloading mechanism is configured to delay the time period in which a round is reloaded into the barrel, after the previous round has been fired.

[0004] BACKGROUND

[0005] The present invention relates to gas-operated, autoloading firearms.

[0006] Gas pressure produced from the combustion process of a shot fired has been used to operate autoloading mechanisms in firearms since the late 1880's. Gas-operated firearms usually include a receiver and a breech-bolt mechanism mounted for reciprocal movement to and from a battery position in the receiver. The bolt mechanism is mechanically linked to a piston assembly located within a cylinder parallel to the gun barrel. The piston assembly is automatically operated by a portion of pressurised combustion gas that is created on discharge of a round. The gas is bled from the gun barrel to the cylinder via a gas passage. Energy of the pressurised gas is converted into mechanical energy through movement of the piston. The piston assembly is configured to mechanically unlock the bolt mechanism after firing, withdraw the bolt mechanism from the battery position, eject the spent cartridge, and advance a fresh cartridge into position for loading into a breech chamber. Simultaneously, an action spring coupled to the bolt mechanism is compressed. Subsequently, the action spring returns the bolt mechanism to the battery position, loading the fresh cartridge into the breech chamber. In such configurations, the time at which peak gas pressure is reached after firing a round is very short, which means that the bolt starts opening / unlocking to reload the next round soon after the previous round has been fired. In some cases, the bolt may start to open at about the same time as the bullet leaves the barrel. For example, in short barrel rifles, the peak pressure is about 15,000 psi at the muzzle and this occurs at around % millisecond after firing (about the same time as when the bullet leaves the barrel) and about the same time as the bolt begins to open / unlock.

[0007] Although early bolt opening helps for speedy reloading of the gun, it also has disadvantages. For example, the high pressure in the barrel drives the bolt and bolt carrier rapidly towards the reloading position, which creates significant wear on the bolt carrier and on any parts that are directly impacted by the moving bolt carrier or that are impacted by one or more intermediary components that are impacted by the bolt carrier, such as a buffer spring and buffer within the gun receiver. The repetitive wear on effected components reduces the time period in which the gun can be safely and reliably used. Another disadvantage of rapid bolt opening is that the high-pressure gas is typically dumped through the ejection port through which the used cartridge is expended - again very shortly after firing. The ejection port is located close to the operator's ear and the sound levels produced by the high pressure being ejected through the ejection port are high, which can cause hearing damage and can negatively impact the sound suppressing effect of the gun through use of a suppressor. Furthermore, the ejected gas includes toxic gases and heavy metals. Because the gas is ejected in front of the operator's face, the toxicity of the gas and its proximity to the operator's mouth and nose is unhealthy. In some cases, the noise and gases produced by known autoloading systems can make it difficult for an operatorto maintain sight of the target.

[0008] United States patent no. 483,539 discloses an early mechanism for autoloading of a gun, which uses gas from the combustion process to drive a piston rod arrangement to reload the gun. Combustion gases pass through a gas passage in the barrel of the gun after the bullet has passed the conduit. The gas passage leads to a cylindrical tube at the side of the barrel and parallel to the barrel and in which is fitted a movable rod or piston, which is adapted to actuate the autoloading mechanism of the gun.

[0009] United States patent n. 471,782 discloses the use of a flapper valve at the front of the barrel that harnesses energy to actuate a lever action in the firearm in order to open the bolt.

[0010] However, both examples have limitations.

[0011] It would therefore be useful to provide an automatic reloading system for a gun that goes at least some way towards overcoming the disadvantages of the prior art, or that at least provides the public with a useful alternative.

[0012] SUMMARY OF INVENTION

[0013] According to one form of the technology there is provided a firearm comprising a reloading delay mechanism, wherein the reloading delay mechanism comprises a piston which is moveable within a pressure chamber between a first position and a second position, wherein the piston is movable from the second position to the first position by pressure from combustion gasses communicated to the pressure chamber from a barrel of the firearm, the piston configured to compress a compression element when moving from the second position to the first position, wherein a force exerted by the compressed compression element moves a bolt carrier group of the firearm during a reloading cycle, and wherein the reloading cycle does not begin before the first piston reaches the first position.

[0014] In examples:

[0015] • the reloading cycle begins no less than 5 ms after the firearm is fired; the reloading cycle begins no less than 15 ms after the firearm is fired; • wherein the reloading cycle begins automatically;

[0016] • the reloading cycle is initiated manually;

[0017] • the piston moves away from the first position during an ejection phase of the reloading cycle;

[0018] • the piston remains in the first position during an ejection phase of the reloading cycle; and / or

[0019] • the first compression member moves the piston from the first position to the second position during or after commencement of the reloading cycle.

[0020] According to another form of the technology there is provided a firearm comprising a reloading delay mechanism comprising a piston within a piston housing, wherein combustion gases from a bullet fired by the firearm cause relative movement between the piston and the piston housing, the relative movement causing movement of an action rod which compresses a compression element, wherein a force exerted by the compressed compression element moves a bolt carrier group of the firearm during a reloading cycle, and wherein the reloading cycle does not begin until at least 5 milliseconds after the firearm is fired.

[0021] According to another form of the technology upper receiver comprising a reloading delay mechanism for a firearm comprising a barrel attached to the upper receiver, wherein the upper receiver comprises a receiver body comprising a hollow interior in which is slidably located a bolt carrier group comprising a bolt carrier, a bolt, and a firing pin; and a buffer system located between the bolt carrier group and a rear end of the receiver body, the buffer system comprising an action spring configured to bias the bolt carrier group towards a forward end of the receiver body, and wherein the reloading system comprises: a piston housing comprising an actuation chamber and a pressure chamberthat is sealed from the actuation chamber and that comprises a first gas passage in fluid communication with the barrel, a first elongate piston received within the piston housing and extending between the actuation chamber and the pressure chamber, the first piston comprising a shaft and a pressure head, and also comprising a first compression member that projects laterally from a portion of the shaft located within the actuation chamber, wherein the pressure head is located at or near a first end of the first piston and is snugly received between sidewalls of the pressure chamber and the first piston is slidable longitudinally within the piston housing between a first position and a second position; wherein the actuation chamber comprises an end stop that is distanced from the first compression member; wherein the reloading delay mechanism also comprises: a first compression element that is located within the actuation chamber between the end stop and the first compression member, the first compression element having a compressible length, wherein the first compression element is compressed when the piston moves towards the first position; and a latch capable of adopting a locked position and an unlocked position by movement of the piston, wherein when the first piston slides to the first position, a hook of the latch projects through an opening in one side of the actuation chamber to engage with the bolt carrier group, thereby driving the bolt carrier towards the rear end of the receiver body when the first compression element moves the piston from the first position to the second position, and wherein, when the piston is in the second position, the latch disengages from the bolt carrier group, allowing the action spring to move the bolt carrier group towards the forward end of the receiver body.

[0022] In examples:

[0023] • the first compression element comprises a spring;

[0024] • the latch is pivotable and is biased to the locked position by a biasing member;

[0025] • the latch is pivotally mounted at or near a second end of the first piston;

[0026] • the first piston comprises a latch mount at the second end of the piston shaft, the latch comprising a hook at or near a first end of the latch and the latch mount comprising a pivot pin and the latch biasing member that presses the latch hook toward the bolt carrier group;

[0027] • the actuation chamber comprises at least one lower guide surface along which the piston is slidable and in which is located an elongate opening, extending along at least a portion of the length of the guide surface, and wherein the latch hook projects through and slides along the elongate opening as the first piston slides within the actuation chamber;

[0028] • the bolt carrier comprises a projecting element comprising a surface inclined toward the first direction that terminates at a transition point to form an abutment surface that projects from a body portion of the bolt carrier, and wherein movement of the first piston in a first direction and toward the first position causes the pivotable latch hook to contact, pivot, and slide across the inclined surface of the bolt carrier, under pressure of the latch biasing member, until the latch hook reaches the transition point of the bolt carrier, at which point the latch hook pivots toward the bolt carrier, under pressure from the biasing member, and hooks against the abutment surface to prevent rearward movement of the bolt carrier group and to thereby prevent reloading of the firearm;

[0029] • the pressure chamber is located forward of the actuation chamber;

[0030] • the actuation chamber and the pressure chamber extend substantially parallel to a longitudinal axis of the barrel.

[0031] • the pressure chamber is distanced from the actuation chamber and is supported on the barrel by a support;

[0032] • the reloading delay mechanism further comprises a piston lock that automatically locks the first piston in the first position, holding the first compression element under compression;

[0033] • the piston lock comprises a moveable locking element that engages with the pressure head in a locked position to prevent movement of the pressure head in a second direction and thereby preventing the first piston from sliding to the second position;

[0034] • the upper receiver further comprises an unlocking member to manually move the piston lock to unlock the piston lock by disengaging the piston lock with the pressure head;

[0035] • the pressure chamber comprises one or more gas outlet ports located proximate to a forward end of the pressure chamber;

[0036] • the one or more gas outlet ports are located behind the pressure head and proximate to the pressure head when the first piston is in the first position;

[0037] • the pressure chamber comprises a first cavity in which a portion of the first piston, including the pressure head, is slidably received, and a second cavity in which a second elongate piston is slidably received, wherein the first gas passage is provided between the barrel and the second cavity and a second gas passage is provided between the second cavity and the first cavity, the second gas passage comprising a gas outlet into the first cavity that is located behind the pressure head when the first piston is in the second position; wherein a second compression element is provided in the second cavity and is located between an end stop of the second cavity and a second compression member of the second piston, wherein a pivotable toggle is provided in the pressure chamber and comprises a first end contactable by the second piston such that the first piston is able to pivot the toggle between an open position and a closed position; wherein the second piston is slidable longitudinally between a first position and a second position and wherein in the first position, the second piston compresses the second compression element between the end stop of the second cavity and the second compression member and the toggle is caused to pivot to a closed position in which the toggle projects behind the pressure head and presses against a contact surface of the pressure head to prevent the pressure head and therefore the first piston from moving in the second direction;

[0038] • the firearm comprises a manual reload member that causes the toggle to release the pressure head to allow the first piston to slide to the second position to release the bolt carrier group and open the bolt;

[0039] • the pressure head comprises a tapered contact surface that allows the toggle to pivot and slide along the contact surface away from the pressure head when spring tension from the first compression element overrides locking action of the toggle, thereby releasing the pressure head and allowing the first piston to slide to the second position;

[0040] • a forward end of the second piston forms the second compression member such that the second compression element is located between the forward end of the second piston and the end stop of the second cavity; and / or

[0041] • the upper receiver comprises a suppressor comprising a Neilsen device and a pivotable locking lever that is moveable between a locked position and an unlocked position, wherein forward movement of the suppressor pivots the locking lever to the locked position to engage with the first piston and hold the first piston in the first position.

[0042] According to anotherform of the technology there is provided a firearm with an upper receiver as described above.

[0043] In examples:

[0044] • the piston moves to the first position when combustion gasses from firing of the firearm are communicated from the barrel to the pressure chamber via the first gas passage; and / or • the piston reaches the first position no less than 5 ms after the firearm is fired.

[0045] According to another form of the technology there is provided a firearm comprising: an upper receiver comprising a reloading delay mechanism and a barrel attached to the upper receiver, wherein the upper receiver comprises a receiver body comprising a hollow interior in which is slidably located a bolt carrier group comprising a bolt carrier, a bolt, and a firing pin; and a buffer system located between the bolt carrier group and a rear end of the receiver body, the buffer system comprising an action spring configured to bias the bolt carrier group towards a forward end of the receiver body, and wherein the reloading system comprises: a piston housing comprising an actuation chamber and a pressure chamber that is sealed from the actuation chamber and that comprises a first gas passage in fluid communication with the barrel, a first elongate piston received within the piston housing and extending between the actuation chamber and the pressure chamber, the first piston comprising a shaft and a pressure head, and also comprising a first compression member that projects laterally from a portion of the shaft located within the actuation chamber, wherein the pressure head is located at or near a first end of the first piston and is snugly received between sidewalls of the pressure chamber and the first piston is slidable longitudinally within the piston housing between a first position and a second position, wherein the first piston moves to the first position when combustion gasses from firing of the firearm are communicated from the barrel to the pressure chamber via the first gas passage; and; wherein the actuation chamber comprises an end stop that is distanced from the first compression member; wherein the reloading delay mechanism also comprises: a first compression element that is located within the actuation chamber between the end stop and the first compression member, the first compression element having a compressible length, wherein the first compression element is compressed when the piston moves towards the first position; and a latch capable of adopting a locked position and an unlocked position by movement of the piston, wherein when the first piston slides to the first position, a hook of the latch projects through an opening in one side of the actuation chamber to engage with the bolt carrier group to begin a reloading cycle, wherein the reloading cycle begins no less than 5 ms after the firearm is fired. In examples:

[0046] • during the reloading cycle, the bolt carrier moves towards the rear end of the receiver body when the first compression element moves the piston from the first position to the second position, and when the piston is in the second position, the latch disengages from the bolt carrier group, allowing the action spring to move the bolt carrier group towards the forward end of the receiver body;

[0047] • the pressure chamber comprises one or more gas outlet ports, and wherein the gas outlet ports are in fluid communication with the first gas passage, via the pressure chamber, when the piston is in the first position; and / or

[0048] • the one or more gas outlet ports are located proximate to the pressure head when the first piston is in the first position.

[0049] According to another form of the technology there is provided a firearm comprising: an upper receiver comprising a reloading delay mechanism and a barrel attached to the upper receiver, wherein the upper receiver comprises a receiver body comprising a hollow interior in which is slidably located a bolt carrier group comprising a bolt carrier, a bolt, and a firing pin; and a buffer system located between the bolt carrier group and a rear end of the receiver body, the buffer system comprising an action spring configured to bias the bolt carrier group towards a forward end of the receiver body, and wherein the reloading system comprises: a piston housing comprising an actuation chamber and a pressure chamber that is sealed from the actuation chamber and that comprises a first gas passage in fluid communication with the barrel, a first elongate piston received within the piston housing and extending between the actuation chamber and the pressure chamber, the first piston comprising a shaft and a pressure head, and also comprising a first compression member that projects laterally from a portion of the shaft, wherein the pressure head is located at or near a first end of the first piston and is snugly received between sidewalls of the pressure chamber and the first piston is slidable longitudinally within the piston housing between a first position and a second position, wherein the first piston moves to the first position when combustion gasses from firing of the firearm are communicated from the barrel to the pressure chamber via the first gas passage; and; wherein the actuation chamber comprises a first compression element that is compressed by the compression member when the piston moves to the first position, wherein, a force exerted by the compressed compression element moves the bolt carrier group rearward during a reloading cycle, and wherein the reloading cycle does not begin before the first piston reaches the first position.

[0050] In examples, the reloading cycle begins no less than 5 ms after the firearm is fired.

[0051] Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise", "comprising", and the like, are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense, that is to say, in the sense of "including, but not limited to".

[0052] Reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any form of suggestion that that prior art forms part of the common general knowledge in the field of endeavour in any country in the world.

[0053] The invention consists in the foregoing and also envisages constructions of which the following gives examples only.

[0054] BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Preferred forms of the invention will now be described by way of example and with reference to the accompanying drawings, in which:

[0056] Figure 1 is an isometric view of one form of upper receiver for a firearm comprising one form of reloading delay mechanism of the invention;

[0057] Figure 2 is an exploded view of the upper receiver of Figure 1;

[0058] Figure 3 is a top view of the upper receiver of Figure 1;

[0059] Figure 4 is a cross-sectional side view taken along line A-A of Figure 3 and showing the upper receiver in a ready to fire position;

[0060] Figure 5 is a cross-sectional end view taken along line B-B of Figure 3;

[0061] Figure 6 is a cross-sectional end view taken along line C-C of Figure 3;

[0062] Figure 7 is a cross-sectional end view taken along line D-D of Figure 3;

[0063] Figure 8 is a cross-sectional view taken along line A-A of Figure 3 and showing the upper receiver after the bullet leaves the barrel;

[0064] Figure 9 is a cross-sectional view taken along line A-A of Figure 3 and showing the upper receiver as the bolt unlocks;

[0065] Figure 10 is a cross-sectional view taken along line G-G of Figure 9; Figure 1 1 is a cross-sectional view taken along line H-H of Figure 9;

[0066] Figure 12 is a cross-sectional view taken along line A-A of Figure 3 and showing the upper receiver as the spent round is extracted;

[0067] Figure 13 is a cross-sectional view taken along line A-A of Figure 3 and showing the upper receiver with the bolt fully open, the bolt carrier group ready to be pushed forward to load another cartridge into the breech chamber;

[0068] Figure 14 is an isometric view of an upper receiver comprising another form of reloading delay mechanism according to the invention;

[0069] Figure 15 is an exploded view of the upper receiver of Figure 14;

[0070] Figure 16 is a partial cut away and partial cross-sectional top view of the upper receiver of Figure 14;

[0071] Figure 17 is a cross-sectional view along lines G-G of Figure 16;

[0072] Figure 18 is a cross-sectional view along lines H-H of Figure 17;

[0073] Figure 19 is a cross-sectional view along lines l-l of Figure 17;

[0074] Figure 20 is a cross-sectional view along lines J-J of Figure 17;

[0075] Figure 21 is a partial cut away and partial cross-sectional top view of the upper receiver of Figure 14 after a round has been fired;

[0076] Figure 22 is a cross-sectional side view of the upper receiver of Figure 21;

[0077] Figure 23 is a partial cut away and partial cross-sectional top view of the upper receiver of Figure 14 and showing the locking lever being disengaged from the bolt carrier group after a round has been fired;

[0078] Figure 24 is a cross-sectional side view of the upper receiver of Figure 23;

[0079] Figure 25 is a partial cut away and partial cross-sectional top view of the upper receiver of Figure 14 and showing the locking lever projecting into the hollow interior of the upper receiver forward of the bolt carrier group, which has moved rearward, so as not to engage with the bolt carrier;

[0080] Figure 26 is a cross-sectional side view of the upper receiver of Figure 25 in which it can be seen that the bolt carrier group has moved rearward;

[0081] Figure 27 is a cross-sectional side view of the upper receiver of Figure 25 in which it can be seen that the bolt carrier group has moved fully rearward to open the bolt and to release the latch from the first piston, to release the first piston from the first position;

[0082] Figure 28 is a top view of an alternative embodiment that includes the features of the embodiment shown in Figures 1 to 14, but also includes a secondary reloading delay mechanism;

[0083] Figure 29 is a cross-sectional view taken along lines K-K showing the upper receiver ready to fire, in which the bolt carrier group is fully forward and engaged with the barrel extension and both the first piston and the second piston are in the second position; Figure 30 is a cross-sectional view taken along lines K-K showing the upper receiver after a bullet has been fired and in which the first and second pistons are in the first position and the first piston is locked in the first position by a locking toggle in the pressure chamber;

[0084] Figure 31 is a cross-sectional view taken along lines K-K showing the upper receiver after the locking toggle releases engagement with the first piston, so that the second piston has returned to its second position and the first piston has started to slide in a second direction toward its second position;

[0085] Figure 32 is a cross-sectional view taken along lines K-K showing the upper receiver as the first piston shaft moves rearward toward the second position, pulling the bolt carrier group rearward;

[0086] Figure 33 is a cross-sectional view taken along lines K-K showing the upper receiver when the bolt is fully open and the first and second pistons are both in the second position;

[0087] Figure 34 is an exploded view of an upper receiver of the invention that also comprises a suppressor;

[0088] Figure 35 is a top view of the upper receiver of Figure 34 in an assembled state;

[0089] Figure 36 is a cross-sectional view taken along lines L-L of Figure 35 just after a bullet has been fired;

[0090] Figure 37 is a cross-sectional view taken along lines L-L of Figure 35 shortly after a bullet has been fired (so after the moment in time captured by Figure 36) and in which the Neilsen device of the suppressor has pushed the suppressor forward, causing a locking lever to engage with the first piston and hold the first piston in the first position;

[0091] Figure 38 is a cross-sectional view taken along lines L-L of Figure 35 at a moment later in time than the moment captured by Figure 37 and in which the Neilsen device has pulled the suppressor body back against the barrel of the upper receiver, causing the locking lever to pivot and disengage with the first piston and thereby to release the first piston from the first position.

[0092] Figure 39 is an isometric view of another form of upper receiver for a firearm comprising one form of reloading delay mechanism of the invention.

[0093] Figure 39A is an exploded view of the upper receiver of Figure 39.

[0094] Figure 40 is a cross-sectional view of the upper receiver of Figure 39 in a ready to fire position.

[0095] Figure 41 is a cross-sectional view of the upper receiver of Figure 39 after the bullet has left the barrel and gas pressure has moved the piston housing and action rod forward.

[0096] Figure 42 is a cross-sectional view of the upper receiver of Figure 39 as the bolt unlocks.

[0097] Figure 43 is a cross-sectional view of the upper receiver of Figure 39 with the bolt carrier group moved rearward for ejection of the shell.

[0098] Figure 44 is an isometric view of another form of upper receiver for a firearm comprising one form of reloading delay mechanism of the invention.

[0099] Figure 44A is an exploded view of the upper receiver of Figure 44.

[0100] Figure 45 is a cross-sectional view of the upper receiver of Figure 44 in a ready to fire position. Figure 45A is an enlarged view of area A of Figure 45, showing a latch between the actuation chamber and the hollow interior of the receiver engaged with the bolt carrier.

[0101] Figure 46 is a cross-sectional view of the upper receiver of Figure 39 after the bullet has left the barrel and gas pressure has moved the piston to the first position and the bolt unlocks.

[0102] Figure 46A is an enlarged view of area B of Figure 46 showing the latch disengaged from the bolt carrier.

[0103] Figure 47 is a cross-sectional view of the upper receiver of Figure 45 with the bolt carrier group moving rearward for ejection of the shell.

[0104] Figure 47A is an enlarged view of area C from Figure 47 showing the locking latch still engaged with the first piston.

[0105] Figure 48 is a cross-sectional view of the upper receiver of Figure 45 with the bolt carrier group moved completely rearward.

[0106] Figure 48A is an enlarged view of area D of Figure 48 showing the bolt carrier group unlatching the locking latch from the piston.

[0107] Figure 49 is an isometric view of another form of upper receiver for a firearm comprising one form of reloading delay mechanism of the invention.

[0108] Figure 49A is an exploded view of the upper receiver of Figure 49.

[0109] Figure 50 is a cross-sectional view of the upper receiver of Figure 49 in a ready to fire position.

[0110] Figure 50A is an enlarged view of area E of Figure 50, showing a latch between the actuation chamber and the hollow interior of the receiver engaged with the bolt carrier.

[0111] Figure 51 is a cross-sectional view of the upper receiver of Figure 49 after the firearm is fired, and with the piston beginning to move and compress the compression element.

[0112] Figure 51 A is an enlarged view of area F of Figure 51 , showing the latch between the actuation chamber and the hollow interior of the receiver remaining engaged with the bolt carrier.

[0113] Figure 52 a cross-sectional view of the upper receiver of Figure 49 with piston rod of the two-part piston separated from the piston head and the bolt carrier group moving backward for ejection of the shell.

[0114] Figure 52A is an enlarged view of area G of Figure 52, showing the latch between the actuation chamber and the hollow interior of the receiver disengaged from the bolt carrier.

[0115] Figure 52B is an enlarged view of area H of Figure 52, showing the locking latch engaged with the piston rod.

[0116] Figure 53 a cross-sectional view of the upper receiver of Figure 49 with piston rod of the two-part piston separated from the piston head and the compression element fully compressed. The bolt carrier group is at its rearmost position.

[0117] Figure 53A an enlarged view of area I of Figure 53, showing the locking latch disengaged from the piston rod to allow the bolt carrier group and the first piston to move back to the ready to fire position. Figure 54 shows a compete firearm comprising a variation of the upper receiver shown in Figures 1 -13.

[0118] Figure 54A is a cross-sectional view of the firearm of Figure 54.

[0119] Figure 54B is an exploded view of the firearm of Figure 54.

[0120] Figure 55 is an isometric view of another form of upper receiver for a firearm comprising one form of reloading delay mechanism of the invention.

[0121] Figure 55A is an exploded view of the upper receiver of the firearm of Figure 55.

[0122] Figure 56 is a plan view of the upper receiver of the firearm of Figures 55, with a partial crosssection view of the pressure chamber, and showing a piston lock in a disengaged position.

[0123] Figure 57 is a plan view of the upper receiver of the firearm of Figures 55, with a partial crosssection view of the pressure chamber, and showing a piston lock engaged with a lock engaging portion.

[0124] Figure 57A is an enlarged view of area J of Figure 57.

[0125] DETAILED DESCRIPTION

[0126] The invention is further described with reference to the following examples. It will be appreciated that the invention as claimed is not intended to be limited in any way by these examples.

[0127] As exemplified by embodiments shown in Figures 1 to 57A, the present invention relates to a reloading delay mechanism for an autoloading firearm / gun and to an autoloading firearm comprising such a reloading delay mechanism. An autoloading firearm may be an automatic or semi-automatic firearm, or the delay mechanism may be manually operated after the potential energy is captured for release at a time determined by the operator.

[0128] Examples of the present invention use the energy of the combustion gases from a fired bullet to move an action rod which compresses a compression element (such as a spring) without moving the bolt carrier. Once the compression element is fully compressed, energy stored in the compression element is released (either automatically or manually) to begin the reloading cycle. In this way the reloading cycle may be delayed by at least 5 milliseconds, for example around 15 ms-30 ms.

[0129] Forward moving examples

[0130] Referring to Figures 1 to 7, the firearm 1000 comprises an upper receiver 1100 that comprises a bolt carrier group 1200, a barrel 1300 comprising a breech chamber, a barrel extension 1350 attached to the barrel and the upper receiver, a charging handle (not shown) operably engageable with the bolt carrier group 1200 to manually load a new cartridge into the breech chamber when necessary. In use the upper receiver 1 100 is attached to a lower receiver 1400 (see Figure 54-54B) comprising at least a trigger assembly 1450 and a removable magazine. The particular design of the lower receiver 1400 forms no part of the invention.

[0131] The bolt carrier group 1200 comprises a bolt carrier 1210, a bolt 1220, and a firing pin 1240.

[0132] The bolt carrier 1210 comprises a body comprising a bolt receiving cavity 121 1 that extends between forward and rearward ends of the bolt carrier 1210 and that is configured to rotatably receive at least a portion of the bolt 1220 therein. The bolt carrier 1210 comprises a projecting element 1214 comprising an inclined surface 1215 that terminates at a transition point to form an abutment surface 1216 that projects outwardly from the bolt carrier 1210, as seen in Fig. 4. The inclined surface 1215 of the bolt carrier 1210 may be inclined in the first direction of movement of the first piston 1620, that is to say, the direction in which the piston 1620 moves to adopt the first position. In preferred forms, the inclined surface 1215 is forwardly inclined toward the muzzle of the firearm.

[0133] The bolt 1220 comprises a pin receiving cavity that extends between forward and rearward ends of the bolt 1220 and is configured to slidingly receive at least a portion of the firing pin 1240 therein. The bolt also comprises a cam pin 1230 that projects from a body of the bolt and engages with a cam race or cam slot provided in the body of the bolt carrier 1210.

[0134] The barrel 1300 is attached to the upper receiver body 1 105 and comprises a tube comprising a proximal end and a distal end 1301 and through which a bullet is fired. The proximal end of the barrel 1300 comprises a breech chamber and is attached to the barrel extension 1350. The barrel extension 1350 is configured to removably engage the bolt 1220 and lock the bolt and bolt carrier group 1200 to the barrel 1300 when the firearm is ready to be fired. By locking the bolt carrier group 1200 to the barrel 1300, and therefore to the upper receiver 1100, the bolt carrier group 1200 is secured in a fixed position when the firearm is fired.

[0135] To attach the bolt 1220 to the barrel extension 1350, the bolt comprises an engagement system typical with autoloading firearms. As shown in Figure 5, the bolt may comprise a series of locking lugs 1221 projecting from a circumferential surface of the bolt 1220 at a first end of the bolt. The bolt locking lugs 1221 terminate partway along the bolt body 1222 so that each lug 1221 comprises a terminal end at the point of termination. The barrel extension 1350 comprises a hollow, tubular cavity comprising a series of barrel extension lugs 1351 and slots that project inwardly from the inner tubular wall of the extension 1350 at the rear of the extension 1350. The barrel extension lugs 1351 terminate partway along the body of the barrel extension, so that each barrel extension lug comprises a terminal end at the point of termination. The locking lugs 1221 are configured to align with the barrel extension slots when the bolt 1220 is in the open / unlocked position, so that the bolt can slide in and out of the barrel extension 1350 by sliding the locking lugs 1221 along the barrel extension slots. The cam pin 1230 is attached to the bolt 1220, which is partially located within and rotatably held within the cavity 1211 of the bolt carrier 1210. The cam pin 1230 projects through a cam race 1212 in the body of the bolt carrier 1210. The cam pin 1230 slides along the cam race 1212 as the bolt 1220 is slid into the barrel extension 1350 and until the pin 1230 reaches a turning point in the cam race that causes the pin 1230 to rotate in a first direction. As the pin 1230 rotates in the first direction, the bolt 1220 is caused to rotate about its longitudinal axis in the first direction. The cam race 1212 and the dimensions of the locking lugs 1221 and barrel extension lugs 1351 are configured so that the bolt 1220 is caused to rotate once the locking lugs 1221 have been slid into the barrel extension 1350 a sufficient distance to move past the barrel extension lugs 1351. The pin 1230 causes the bolt 1220 to rotate sufficiently to allow the terminal ends of the locking lugs to substantially align with the terminal ends of the bolt extension lugs, so that the abutment of the terminal ends of the locking lugs and bolt extension lugs prevents the bolt 1220 from being pulled out of the barrel extension 1350, thereby locking the bolt and the bolt carrier group 1200 to the barrel extension 1350 and therefore to the barrel 1300 and upper receiver 1 100. In the locked, battery position, the bolt 1220 pushes up against a breech face of the barrel 1300 and the cam pin is locked within the cam race 1212 by engaging with an engagement feature, such as a recess in the body 1 105 of the upper receiver 1100.

[0136] The interior cavity of the barrel extension 1350 aligns with the hollow tube of the barrel 1300. The first end of the bolt 1220 is configured to removably attach to a cartridge of an ammunition round. Thus, by inserting the bolt (attached to a cartridge) into the barrel extension 1350, the bolt 1220 is able to load the cartridge into the barrel 1300.

[0137] The upper receiver 1100 comprises a body 1 105 comprising a hollow interior 1 110 for receiving at least a portion of the bolt carrier group 1200 therein. The upper receiver 1 100 comprises a forward end and a rearward end. The forward end is attachable to the barrel extension 1350. The upper receiver also comprises an ejection port 1 120 through which a spent cartridge is ejected, and optionally comprises an ejection port cover to prevent dust and debris entering the interior of the upper receiver 1 100 through the ejection port.

[0138] The bolt carrier group 1200 is slidably received within the hollow 1 110 of the upper receiver 1100 and is configured to slide forward as the bolt 1220 attaches to the barrel extension 1350, and to slide backward as the bolt 1220 opens and disengages from the barrel extension 1350.

[0139] The upper receiver 1 100 also comprises a buffer 1 130 and a buffer spring / action spring 1 140, both of which are also located in the hollow 1 110 of the upper receiver and between the rearward end of the upper receiver and the bolt carrier 1210. The buffer / action spring 1140 extends between a rear surface of the bolt carrier 1210 and the buffer 1 130, which is typically located at the rear of the hollow 1 110 of the upper receiver 1100. The buffer / action spring 1 140 is configured to press against the buffer 1130 and compress as the bolt carrier group 1200 slides rearward within the hollow 11 10 to open the bolt 1220 and reload the firearm 1000. The spring tension within the compressed buffer / action spring 1140 is used to then drive the bolt carrier group 1200 forward into the battery position, in which the bolt 1220 loads a new cartridge into the barrel 1300 and locks the bolt carrier group 1200 against the barrel extension 1350.

[0140] The upper receiver 1 100 also comprises a reloading mechanism that comprises a piston housing 1610 that may be substantially parallel to the hollow 1 110 of the upper receiver. The piston housing 1610 comprises an actuation chamber 1611 and a pressure chamber 1661 and is configured to slidably receive a first piston 1620 therein. In some forms, the pressure chamber 1661 may comprise a gas block.

[0141] The actuation chamber 161 1 comprises a first end wall 1612 located at a forward end of the chamber and a second end wall 1613 located at a rearward end of the chamber 161 1. At least one side wall 1614 extends between the first and second end walls 1612, 1613. At least one guide element 1605, such as a dividing wall or one or more rails may separate the actuation chamber from the hollow 11 10 within the upper receiver 1100. The guide element 1605, first and second ends 1612, 1613, and the side wall 1614 define a cavity within the actuation chamber 161 1.

[0142] Preferably, the pressure chamber 1661 is located forward of the actuation chamber 161 1. In some forms, the pressure chamber comprises a first end 1662 at a forward end of the chamber 1661 and a second end 1663 at a rearward end of the chamber 1661. In some forms, end walls may be provided at the first and second ends 1662, 1663 of the pressure chamber. In other forms, an opening may be provided at the first end 1662 of the pressure chamber 1661. At least one side wall 1664 extends between the first and second ends of the pressure chamber, such that the ends 1662, 1663 and side wall(s) 1664 define a cavity within the pressure chamber 1661. The pressure chamber 1661 comprises a first gas passage 1310 that is in fluid communication with the barrel 1300. In some forms, the pressure chamber 1661 may form an elongate tube and may be located substantially parallel to and proximate to the barrel 1300. In some forms, the pressure chamber 1661 is supported by a support 1667 that is located between the barrel 1300 and the pressure chamber 1661 . In some forms, the support may comprise a step machined into the barrel.

[0143] The piston housing may be formed as a single part or in two separate parts in which the actuation chamber 161 1 and the pressure chamber 1662 are distanced from each other and a space is provided in between.

[0144] In some forms, the piston housing comprising the actuation chamber 161 1 and pressure chamber 1661 is located in the upper receiver above the hollow interior 11 10 of the upper receiver and the barrel 1300.

[0145] An elongate first piston 1620 is received within the piston housing and extends between the actuation chamber 161 1 and the pressure chamber 1661 so that a portion of the first piston 1620 is slidably received within the actuation chamber 161 1 and a portion of the first piston 1620 is slidably received within the pressure chamber 1661. An action rod 2000 is provided which can compress a first compression element 1630. In many examples the action rod 2000 comprises a piston shaft 1621. The first piston 1620 comprises the elongate shaft 1621 , a pressure head 1622, and a compression member 1623.

[0146] The pressure head 1622 is located at or near a first end of the shaft 1621 and within the pressure chamber 1661 . The pressure head 1622 is snugly and slidably received between side walls of the pressure chamber. In some forms, the pressure head 1622 forms a piston head. An opening 1665 is provided in the second end wall 1663 of the pressure chamber 1661 to allow the piston shaft 1621 to extend therethough. The shaft 1621 is slidable within the opening 1665, such that a central portion of the shaft 1621 may extend between the actuation chamber 161 1 and the pressure chamber 1661 .

[0147] The compression member 1623 projects laterally from a portion of the shaft and is located within the actuation chamber 161 1. In some forms, as shown in Figure 2, the compression member 1623 consists of a latch mount 1624 located at the second end of the first piston 1620. In other words, the latch mount 1624 serves as a compression member 1623. In other forms, a circumferential flange may project from the shaft 1621 of the first piston 1620 to form a compression member.

[0148] The first piston 1620 also comprises a second end located at an opposing end to the first end of the piston. In some forms, the compression member 1623 forms a foot of the first piston 1620 and is located at or near the second end of the first piston.

[0149] The first piston 1620 is slidable longitudinally within the piston housing (i.e., within the actuation chamber 1611 and the pressure chamber 1661) between a first position and a second position. Sliding the first piston 1620 in a first direction, moves the piston 1620 toward the first position, whereas sliding the first piston 1620 s in a second direction, moves the piston towards the second position.

[0150] The actuation chamber 161 1 comprises a stop 1615 that opposes the compression member 1623 of the first piston 1620 and is distanced from the compression member 1623. In some forms, the stop 1615 of the actuation chamber 1611 is located forward of the compression member 1623. In some forms, the stop 1615 forms the first end wall of the actuation chamber 1611.

[0151] A first compression element 1630 is located within the actuation chamber between the stop 1615 and the compression member 1623 and has a compressible length such that the compression element is configured to compress and expand after compression. In some forms, the compression element 1630 comprises a compression spring. Preferably, the compression spring surrounds a portion of the piston shaft 1621.

[0152] The reloading mechanism also comprises a latch 1640 capable of adopting a locked position and an unlocked position by movement of the first piston 1620. For example, when the first piston slides to the first position, a hook of the latch may project through an opening in one side of the actuation chamber 161 1 to engage with the bolt carrier group 1200. In some forms, the latch 1640 is a pivotable latch configured to pivot between the locked position and the unlocked position. In some forms, the latch 1640 is pivotally mounted at or near the second end of the first piston 1620. The latch 1640 comprises a hook 1641 configured to engage with the bolt carrier group 1200, such as with the bolt carrier 1210, to provide rearward movement of the bolt carrier group 1200 with the piston 1620 when engaged. In preferred forms, a biasing member 1645 biases the latch 1640 to the locked position. When in locked position, the latch may engage with the bolt carrier 1210 and the latch biasing member 1645 presses the latch hook against the bolt carrier. The biasing member 1645 may take any suitable form to bias the latch 1640 to a locked position, but preferably comprises a spring, such as a compression spring, a tension spring, a leaf spring or the like. In the embodiment shown in Figure 7, the biasing member 1645 is a compression spring.

[0153] In some forms, the first piston 1620 comprises a latch mount 1624 at the second end of the piston shaft 1621. In some forms, the latch mount is removably attachable to the first piston shaft 1621. For example, the latch mount may comprise a milled slot at a first / forward end of the latch mount that allows a piston ball joint provided in second end of the piston shaft 1621 to connect with the match mount 1624 in a manner that does not induce fatigue.

[0154] The latch mount may be configured to pivotably mount the latch 1640 thereon. In some forms, the latch hook 1641 is located at or near a first end of the latch and the latch mount 1624 comprises a pivot pin about which the latch 1640 can pivot to move the hook 1641 toward and away from the bolt carrier group 1200 in the upper receiver 1100.

[0155] In some forms, the guide element 1605 of the actuation chamber 1611 is located beneath the first piston 1620 and provides a guide surface along which the first piston 1620 is slidable between the first and second positions. In some forms, an opening 1605a is provided in the guide element 1605 through which the latch hook 1641 may project. In preferred forms, the opening 1605a is an elongate opening that extends along at least a portion of the length of the guide element 1605, such that the latch hook 1641 is able to project through and slide along the elongate opening 1605a as the first piston 1620 slides within the actuation chamber 161 1.

[0156] In some forms, one or more gas outlet ports 1 150 may be provided in the pressure chamber 1661 . The one or more gas outlet ports are preferably located on the side wall(s) of the pressure chamber 1661 , and are located behind the pressure head 1662 and proximate to the pressure head 1662 when the first piston 1620 is in the first position. Preferably, the gas ports 1150 are located near the first end 1662 of the pressure chamber 1661 to eject gas from a position which is spaced away from the face of the operator of the firearm. In some forms, the gas ports 1 150 may eject gas into a secondary chamber to delay venting. In some forms, the pressure head 1622 comprises a thickness t and the gas ports 1150 are located at a distance d from the first end 1662 of the pressure chamber 1661, where t < d, such that when the pressure head 1622 is pushed proximate to the first end 1662 at the end of the piston stroke, the gas port(s) 1 150 are not obscured by the pressure head 1622.

[0157] The lower receiver is attached to the upper receiver 1 100 and includes a trigger that is operably connected to a spring-charged hammer. The lower receiver and its components are well known and are not illustrated herein. The hammer is operably engaged with the trigger, via a sear, and with the firing pin.

[0158] In use, as shown best in Figures 4, 8, 9, 12, and 13, opening the charging handle (not shown) moves the bolt carrier group 1200 backward within the hollow 1 110 of the upper receiver, initially compressing the buffer / action spring 1 140 and then allowing the spring 1 140 to release. As the buffer / action spring 1140 releases, the bolt carrier group 1200 moves forward, stripping a top cartridge from the magazine and guiding the cartridge into the breech chamber of the barrel 1300. The firearm is now ready to fire. Movement of the bolt carrier backward then forward (whether under the action of a charging handle, or the reloading system) may be referred to as a reloading cycle.

[0159] Pulling the trigger causes the sear to release the hammer which drives the firing pin 1240 forward through a cavity in the bolt 1 120 until the pin 1240 impacts on the rear end of the cartridge held within the bolt 1220, causing a detonation within the cartridge that fires the bullet (located at the front end of the cartridge) through the barrel 1300.

[0160] Expanding combustion gases from the cartridge detonation follow the bullet along the barrel 1300. At least a portion of the gases escape through the first gas passage 1310 in the barrel 1300 and into the pressure chamber 1661, pushing against the pressure head 1622 to push the first piston 1620 in a first direction and toward the first position. As shown in Figure 8, movement of the first piston in the first direction pushes the pressure head forward within the pressure chamber 1661. As the first piston 1620 moves in the first direction, the piston compression member 1623 pushes against the compression element 1630, compressing the compression element 1630 within the actuation cavity 1611 and between the compression member 1623 and the stop 1615. The compressed compression element 1630 now holds increased spring tension.

[0161] As the first piston 1620 moves in the first direction, the piston 1620 slides along the guide element 1605 and the latch hook 1641 projects through the opening 1605a in the guide element to contact the bolt carrier when the piston 1620 has moved sufficiently in the first direction for the latch 1640 to reach the bolt carrier 1610. The latch hook 1641 slides across the inclined surface 1215 of the projecting element 1214 of the bolt carrier 1610, under pressure from the latch biasing member 1645 as the first piston 1620 moves in the first direction.

[0162] The high-pressure gases continue to push the first piston 1620 in the first direction until the pressure head 1622 comes proximate to the first end 1662 of the pressure chamber 1661 . Simultaneously or just prior to the head 1622 reaching the first end 1662, the latch hook 1641 of the latch 1640 (which is attached to the first piston 1620 and therefore moves with the first piston) reaches the transition point of the bolt carrier 1610. At the transition point, the projecting element 1214 terminates and stops pressing against the latch hook 1641 , allowing the latch 1640 to pivot so that the latch hook pivots toward the bolt carrier 1610, under pressure from the latch biasing member 1645. The latch hook 1641 hooks against the abutment surface 1216 of the bolt carrier 1610. At this point, the bolt carrier group 1200 and the first piston 1620 are coupled together.

[0163] The time taken for the first piston 1620 to complete the movement to the first position depends on a number of factors, including the force exerted on the piston head 1622 by the combustion gasses, the spring rate and preload of the compression element 1630, and mass of the piston 1620. These may be selected to provide a required delay between the firing of the firearm and the beginning of a reloading cycle. In preferred embodiments, the reloading cycle is delayed by at least 5 ms, for example 15-30 ms, or 15-50 ms from the firing of the firearm.

[0164] As the pressure head 1622 passes the gas outlet port(s) 1666 and reaches the first position, as shown in Figure 8, the gas is ejected through the ports 1666, releasing gas pressure from the pressure chamber. This gas is therefore released near the front of the firearm and away from the operator's face and ears. Where a suppressor is attached to the firearm, the gas may be released into the suppressor to muffle any noise.

[0165] The spring tension of the first compression element 1630 pushes against the compression member 1623 of the first piston 1620, which pushes the bolt carrier group 1200 backward to open the bolt by extracting the bolt 1220 from the barrel extension 1350. The compression element 1630 is able to push the piston 1620 in this direction due to the venting of the gases through the ports 1666 resulting in reduced pressure in the pressure chamber.

[0166] In some forms, the reloading delay mechanism of the invention comprises an automatic locking system that locks the first piston 1620 in the first position (such as the forwardmost position) to hold the compression element 1630 under compression before spring tension from the compression element 1630 causes the bolt carrier group 1200 to slide backward and open the bolt. In such an arrangement, the reloading delay mechanism may comprise a piston lock that automatically locks the first piston 1620 in the first position.

[0167] As seen in Figures 55-57A, the piston lock 2050 may comprise a pivoting lock 2060 comprising a hooked member 2070 which is pivotally attached to a side wall 1614 of the pressure chamber. The first piston 1620 may comprise a lock engaging portion 2090 which extends forward of the pressure head 1622. The lock engaging portion 2090 may comprise a beveled or dome shaped head 2100, best seen in Figures 57A. The hooked member 2070 may be biased towards the first piston 1620 by a biasing means 2110.

[0168] When the first piston 1622 moves to the first position, the lock engaging portion 2090 moves past the hooked member 2070. In doing so, the beveled front surface of the lock engaging portion 2090 moves the hooked member 2070 sideways against the force of the biasing means 2110, as shown in Figure 56. Once the lock engaging portion 2090 has moved past the hooked member 2070, the biasing means 2110 moves the hooked member 2070 into position behind the lock engaging portion 2090, as shown in Figure 57 and 57A. The tension of the compression element 1630 pulls the first piston 1620 in a second direction, toward the compression element 1630, so that the pivoting lock 2060 jams against the base of the lock engaging portion 2090 and prevents rearward movement (or further rearward movement) of the first piston 1620. Thus, the pivoting lock 2060 holds the first piston 1620 in the first position and holds the compression element 1630 in the compressed position, conserving tension within the compression element 1630. The reloading cycle may be commenced by using a lever 2120 to move the hooked member 2070 out of engagement with the lock engaging portion 2090, thereby allowing the first piston 1620 to move back to the second position. Of course, this is just one possible arrangement of the pivoting lock 2050, other suitable arrangements may be used as would be appreciated by a person skilled in the art.

[0169] In some forms (not shown), the piston lock comprises a moveable locking element that engages with the pressure head 1622 in a locked position to prevent movement of the pressure head in the second direction, thereby preventing the first piston 1620 from sliding to the second position.

[0170] In some forms, the piston lock may comprise a pivoting lock that is biased to a locked position by a lock biasing member or by gravity. The pivoting lock may extend into the pressure chamber 1661 and may be configured to pivot to an open position by pivoting in the direction of movement of the first piston 1620 as piston 1620 slides in the first direction and the pressure head 1622 pushes past the pivoting lock. However, once the pressure head 1622 passes the pivoting lock fully, the pivoting lock may automatically return to a closed position in which the pivoting lock projects into the cavity of the pressure chamber 1661 and is unable to pivot beyond 90° due to the proximity of the piston shaft 1621. The tension of the compression element 1630 pulls the first piston 1620 in a second direction, toward the compression element 1630, so that the pivoting lock jams against the base of the pressure head 1622 and prevents rearward movement (or further rearward movement) of the first piston 1620. Thus, the pivoting lock holds the first piston 1620 in the first position and holds the compression element 1630 in the compressed position, conserving tension within the compression element 1630. Of course, this is just one possible arrangement of the pivoting lock, other suitable arrangements may be used as would be appreciated by a person skilled in the art.

[0171] In some forms, the automatic lock system may comprise an unlocking memberto allow an operator to manually move and unlock the piston lock by disengaging the piston lock with the pressure head 1622. For example, the automatic lock system may comprise a manual release lever that, upon actuation, rotates the pivot lock to release the pressure head 1622, thereby allowing the pressure head 1622 and first piston 1620 to move in the second direction, toward the second position. The automatic lock mechanism allows the mechanical energy produced by the combustion gases to be held as tension in the compression element 1630, for use to reload the firearm 1000 at a later time. In another form of the invention, rather than a mechanism which engages the piston, a manually disengageable latch may be provided to lock the bolt carrier group in its forward position, such that the piston cannot move from the first position to the second position until the latch is manually disengaged and the bolt carrier group is allowed to move. Such a latch may comprise a pivotable locking lever such as that described below with reference to Figures 14 to 27. Alternatively, where manually actuated pivoting latches are described herein, a latch which moves linearly into and out of engagement with the relevant component (e.g. bolt carrier group, lock engaging portion, etc) may be used.

[0172] Regardless of whether the reloading delay mechanism of the invention includes an automatic locking system to lock the first piston 1620 in the first position, or the reloading delay mechanism does not have an automatic locking system, when the first piston 1620 reaches the first position (or is released from being automatically locked in the first position, as the case may be), the spring tension in the compression element 1630 pushes against the compression member 1623 of the first piston 1620, driving the first piston 1620 in a second direction (such as a rearward direction in the embodiments shown in Figures 9, 12, and 13) to expand the compression element 1630 and release its spring tension.

[0173] Because the latch 1640 is engaged with the bolt carrier 1210, the bolt carrier is pulled backward in the second direction as the first piston 1620 is pulled in the second direction. As the bolt carrier 1210 moves backward, the cam pin 1230 of the bolt 1220 is slid within the cam race 1212 causing the bolt 1220 to rotate in a second direction to unlock the bolt from the barrel extension 1350. As the bolt 1220 rotates, the bolt locking lugs 1221 align with slots within the barrel extension 1350 and are free to slide along the slots to extract the bolt 1220 from the barrel extension 1350. Once the bolt 1620 is removed from the barrel extension 1350, the entire bolt carrier group 1200 is extracted from the barrel extension 1350 and rapidly moves backward toward the buffer 1130, compressing the action / buffer spring 1 140.

[0174] The bolt 1220 comprises an extractor at its forward end that grips the rim of the spent cartridge and pulls the cartridge out of the breech chamber as the bolt carrier group 1200 moves backward. The extractor may include a spring-powered ejection mechanism that pushes the cartridge through a side opening 1213 in the bolt carrier 1210 and through the ejection port 1 120 of the upper receiver 1 100.

[0175] The compressed buffer / action spring 1140 now holds spring tension momentarily before the spring tension overcomes the rearward motion of the bolt carrier group 1200, causing the buffer spring 1 140 to release its tension. As the buffer / action spring 1 140 releases, the bolt carrier group 1200 moves forward, stripping a top cartridge from the magazine and guiding the cartridge into the breech chamber of the barrel 1300. The reloading cycle is now complete and the firearm is ready to fire again, as shown in Figure 4.

[0176] Therefore, by using the combustion gas to drive the first piston 1620 to a first position, whereupon the gas is released through the gas outlet port(s) 1666 near a forward end of the firearm, and using spring tension to subsequently pull the first piston 1620 a second direction and cause the bolt carrier group 1200 move backward and to reload the firearm 1000, the reloading delay mechanism of the invention creates a delay between peak gas pressure in the barrel and opening of the bolt 1220. The delay allows some of the energy within the firearm to dissipate before the bolt 1220 is opened. Delaying ejection of the cartridge case also allows the case to cool and contract, improving reliability of ejection. The invention also allows the gas to be ejected near the forward end of the firearm 1000, away from an operator's face, reducing the operator's exposure to toxic gases and locating the noise from the gas ejection further away from the operator's ears. The noise can be further muffled by locating a suppressor over both the nozzle of the barrel 1300 and the gas outlet port(s) 1666. The bolt carrier 1210, buffer / action spring 1 140 and the buffer 1 130 are all decoupled from the combustion gas pressure during the reloading cycle, thereby reducing wear on these components.

[0177] The invention may be particularly useful for firearms which are used with suppressors, since the additional back-pressure caused by the suppressor may exacerbate the problems mentioned above. Use of a typical suppressor may require the reloading cycle to be delayed by at least 15 ms. However, some specially designed suppressors which allow a high flow rate of gases may only require a 5 ms delay.

[0178] Referring next to Figures 54-54B, a firearm 1000 is shown with a variation of the upper receiver 1100 described above. The upper receiver shown in Figures 54-54B may be substantially identical to that described above, with the exception that:

[0179] • a single buffer / action spring 1140 is provided;

[0180] • the receiver 1 100 comprises a buffer tube 1 106 which forms an extension of the receiver body 1 105 and houses the action spring 1140; and

[0181] • the buffer 1 130 comprises a buffer mass 1 130A between the bolt carrier group 1200 and the buffer / action spring 1 140.

[0182] The single buffer spring, buffer tube and buffer mass may all be substantially as is commonly used in conventional firearms.

[0183] The upper receiver 1100 is connected to a lower receiver 1400. The firearm 100 is further provided with a stock 1500.

[0184] Other examples of upper receivers 1100 described herein may combined with a lower receiver 1400, such as the one shown in Figures 54-54B, to form a firearm.

[0185] Referring next to Figs. 39-43, in another form of the technology the piston 1620 may not move relative to the barrel 1300 of the firearm. Instead, the piston housing 1610 may be slidable relative to the barrel 1300 of the firearm and may be connected to the action rod 2000 (equivalent to the piston shaft 1621 described above).

[0186] The piston housing 1620 may move forward to a first position when combustion gases enter the pressure chamber 1661 through a gas passage 1310 provided through the piston 1620. Movement of the piston housing 1620 moves the action rod 2000 in the same way movement of the pressure head 1622 moves the piston shaft 1621 in the example described above. One or more gas outlet ports may be provided in the piston housing 1610 at a position which exposes the ports to the gas within the pressure chamber 1661 when the piston housing 1610 reaches the first (forwardmost) position. The port(s) may take the form of a slot or opening 1666A which moves forward of the piston 1620 when the piston housing is in the first position, creating a path to atmosphere for the combustion gases.

[0187] Operation of the remainder of the mechanism may otherwise be the same as the example described with reference to Figures 1 -13.

[0188] Rear moving examples

[0189] It should be appreciated that the reloading delay mechanism may be configured so that the first piston can be moved in reverse without departing from the invention. In such embodiments, the reloading delay mechanism includes the same or similar features to those used in the embodiment of Figures 1 to 13 and therefore like features are described with like references but with the additional distinction of '. For example, Figures 14 to 27 show another embodiment of the invention in which first gas passage 1310' allows combustion gases to escape from the barrel 1300' to the pressure chamber 1661' after a shot has been fired. The combustion gases press against the pressure head 1622', pushing the first piston 1620' (rearward) in a first direction toward a first position. In this embodiment, the bolt carrier group 1200' comprises a bolt carrier group compression member 1250', best seen in Figures 15 and 17. In some forms, first and second end walls 1612', 1613' form the first and second ends of the actuation chamber. An enlarged opening 1616 may be provided at the first end of the actuation chamber 1611', such as within the first end wall 1612' (or the actuation chamber may exclude a first end wall 1612'), to allow the first piston 1620' and the first compression element 1630' to move back and forth within the opening.

[0190] A compression member 1623' may extend from the first piston shaft 1621 '. In preferred forms, the compression member 1623' extends from the first piston shaft 1621' between first and second ends of the shaft 1621', as shown in Figures 17, 22, 24 and 26. In some forms, the compression member may comprise a circumferential flange extending laterally from the first piston shaft 1621', intermediate the pressure head 1622' and the second end / tail end of the first piston 1620'.

[0191] The compression member 1623' may be configured to press against the first compression element 1630' to compress the first compression element 1630' against the bolt carrier group compression member 1250' as the first piston 1620' is pushed rearward by the gases. Pressure from the compression member 1623' compresses the compression element 1630' between the bolt carrier compression member 1250' and the compression member 1623', placing the compression element 1630' under (compressive) tension.

[0192] An automatic locking system may be employed to hold the first piston 1620' in the first (rearward- most) position so that the spring tension in the compression element 1630' can be utilized at a later time to open and reload the bolt 1220. In some forms, the automatic locking system may comprise a pivotable latch that engages with the pressure head 1622' when the first piston 1620 is in the first position to prevent the first piston from siding in a second direction toward the second position. Again, a manual unlocking system may be provided to allow an operator to manually unlock the first piston 1620' to allow opening of the bolt 1610'.

[0193] However, in other forms, as shown in Figures 14 to 27, the automatic locking system may comprise a pivotable locking latch 1710 that engages with a detent provided in the first piston 1620', such as in the shaft 1621' of the first piston and near the rearward end of the first piston 1620', as shown in Figure 15. The locking latch 1710 is pivotable between a locked position, in which the latch 1710 is engaged with the first piston 1620', and an unlocked position, in which the latch 1710 is disengaged from the first piston 1620'. In preferred forms, the latch 1710 is biased to the locked position by a latch biasing member 1720, such as a spring or the like. For example, the locking latch may be pivotable about a pivot pin and may comprise a first end and a second end with the pivot pin being located between these two ends. As shown in Figure 17, the first end of the locking latch 1710 may comprise a locking feature 171 1, such as a hook, pawl, or the like that engages with the first piston 1620', such as with a detent 1625 in the first piston shaft 1621'. The second end of the locking latch 1710 may comprise a contact surface that directly or indirectly contacts the biasing member such that the biasing member presses against the second end of the locking latch 1710 to pivot the first end of the locking latch 1710 toward the piston 1620'. Preferably, the locking latch 1710 engages with a detent 1625 of the piston 1620' and the detent is provided near the rear end of the piston, at which the piston 1620' forms a locking head 1626 comprising a contact surface 1626a that abuts the locking feature 171 1 or hook of the locking latch 1710 when the first piston 1620' is locked in the first position.

[0194] When the first piston 1620' reaches the first position, a second pivotable locking lever 1730, which is also biased to the locked position by a second biasing member 1740, engages with the bolt carrier 1210' to prevent rearward movement of the bolt carrier group. Thus, locking the bolt 1220' closed to delay automatic opening of the bolt 1220'.

[0195] In some forms, the second pivotable locking lever 1730 comprises a first end (comprising a locking element 1731, such as a contact surface, a hook, pawl, or the like), and a second end, comprising a locking arm 1732. A pivot point is located between the first and second ends at which the second pivotable locking lever 1730 pivots about a pivot pin.

[0196] In operation, as the bolt carrier group moves forward and the bolt 1220' is opened so that the firearm is ready to fire, as shown in Figure 17, an engagement feature of the bolt carrier is engaged by the locking element of the locking lever 1730. In some forms, the engagement feature may be an opening or recess in the bolt carrier body, but in other forms, the engagement feature 1217 comprises a rear surface, such as a rear wall, of the bolt carrier 1210', that is contacted by the locking lever 1730 such that the locking element 1731 extends behind the bolt carrier 1210' and abuts the rear wall of the bolter carrier 1210', preventing rearward movement of the bolt carrier group and opening of the bolt 1220'.

[0197] As shown in Figures 21 to 24, after a round is fired, the first piston shaft 1620' slides rearward to the first position and is locked in the first position by the locking latch 1710. The locking element of the locking lever 1730 continues to project into the interior 1110' of the upper receiver and behind the bolt carrier 1610'.

[0198] A manually operated release mechanism may be employed to disengage the second pivotable locking lever 1730 from the bolt carrier 1210' to allow the bolt carrier group to move rearward in order to open the bolt 1220'. In some forms, as shown best in Figures 21 , 23, and 25, the locking arm 1732 of the locking lever 1730 may be accessible by an operator, who may manually move the locking arm to pivot the locking lever so that the locking element 1731 pivots away from the bolt carrier 1210' to disengage with the bolt carrier group. The locking lever 1730 is configured so that as the bolt carrier group moves forward again after the bolt has been opened, the bolt carrier 1210' slides over a sloping surface of the locking element 1731 , pushing the locking element away until the bolt carrier 1210' passes the locking element 1731, at which point the biasing force from the biasing member 1740 pushes the locking lever 1730 to the locked position in which the locking element extends behind the bolt carrier 1210' again.

[0199] Release of the bolt carrier group allows for the spring tension in the compression element 1630' to drive the bolt carrier group rearward. The bolt carrier 1210', in its rearwardmost position, comprises a trip element that contacts the locking latch 1710, pushing the latch open and away from the first piston 1620', therefore releasing the piston 1620' so that the piston 1620' is able to slide forward again to the second / forwardmost position when the firearm releases a round.

[0200] In examples, the pressure chamber may be provided with gas outlet ports near the first position of the pressure head 1622'. However, since such outlet ports would be relatively close to the user of the firearm, in other examples, no gas outlet ports are provided, and the combustion gases may escape the pressure chamber through the first gas passage 1310' when the pressure in the barrel falls below the pressure in the pressure chamber.

[0201] Referring next to Figures 44-48, a fully automatic variant of the example described above with reference to Figs. 14-27 is shown. In this example the second pivotable locking lever 1730 is omitted.

[0202] The portion of the first piston 1620' between the pressure head 1622' and the compression member 1623' may have an enlarged diameter compared to the action rod 2000 (piston shaft 1621'). In examples, the diameter of the first piston 1620' may be substantially constant between the compression member 1623' and the pressure head 1622'.

[0203] A pivotable latch 2010 may be provided to the body 1105 of the upper receiver 1 100, between the actuation chamber 161 1 and the hollow interior 11 10. The latch 2010 comprises a hook 2012 and a biasing member 2020. The bolt carrier comprises an inclined surface 2022 and abutment surface 2024, similar to those of the example described above with reference to Figs. 1 -13, but in an opposite orientation.

[0204] The biasing member 2020 biases the hook 2012 into engagement with the abutment surface 2024 when the firearm is in a position ready for firing (see Figs. 45 and 45A), thereby holding the bolt carrier in the firing position. When combustion gases move the first piston 1610' to the first position (see Fig. 46 and 46A) the portion of the piston 1610' between the pressure head 1622' and the compression member 1623' contacts a lever 2026 of the latch 2010, moving the hook 2012 out of engagement with the abutment surface 2024 (see Fig. 46A) and allowing the reloading cycle to commence. The operation of the mechanism is thereafter substantially the same as that described above with reference to Figs. 14-27. When the piston is moved back to the second position the latch is free to move back to the required position to engage the abutment surface when the bolt carrier returns to the firing position.

[0205] Referring next to Figs. 49-53, another variation of the example shown in Figs. 44-48 is provided. In this example the first piston is formed in two separate parts 1620A, 1620B, with the pressure head 1622' being separate from the compression member 1623' and action rod 2000 / piston shaft 1621'. The pressure head 1622' is connected to a short pressure head rod portion 2030 which extends out of the pressure chamber 1661'.

[0206] In this example, the pressure chamber 1661' has a shorter length than the distance necessary to fully compress the first compression element 1630'. Movement of the pressure head 1622' causes the pressure head rod 2030 to rapidly accelerate the enlarged diameter portion / compression member 1623' and action rod 2000 / piston shaft 1621' rearward. When the pressure head 1622' reaches its first position (at the end of the pressure chamber 1661'), the second portion 1620B is moving sufficiently quickly that its momentum causes it to continue to move rearward until the locking head 1626 engages the locking latch 1710, as described above with reference to Figs. 44-48. From this point, operation of the mechanism is substantially the same as that described above with reference to Figs. 44-48. Movement of the action rod 2000 / piston shaft 1621' back to its initial position pushes the first part of the piston to its second position.

[0207] It will be appreciated that two-part pistons may also be used with any of the other examples described above.

[0208] Secondary delay

[0209] In one form, the reloading delay mechanism may comprise a secondary delay mechanism to further delay between firing a round and opening the bolt 1220. Such an embodiment may be particularly useful in short barrel rifles, in which the length of the first piston shaft 1621 may be significantly shorter than that of other firearms. Figures 30 to 35 exemplify such an embodiment, in which the pressure chamber is divided into a first cavity 1668 in which a portion of the first piston 1620 is slidably received, and a second cavity 1669 in which a second piston 1670 is slidably received. The second piston comprises a shaft 1671 and a compression member 1673. In some forms, as shown, the first cavity 1668 is located above the second cavity 1669, but in other forms, the second cavity may be located above and may be supported by the first cavity.

[0210] The first gas passage 1310 is provided between the barrel 1300 and the first cavity 1668 and a second gas passage 1680 is provided between the first cavity 1668 and the second cavity 1669. The second gas passage 1680 comprises a gas outlet from the first cavity 1668 that is located between the first and second ends 1662, 1663 of the pressure chamber 1661 and behind the pressure head 1622 when the first piston 1620 is in the first position. Preferably, the second gas passage 1680 is located closer to the second end of the pressure chamber than to the first end of the pressure chamber 1661 .

[0211] The second cavity 1669 comprises a second compression element 1690 that is located between an end stop of the second cavity 1669 and a compression member 1673 of the second piston 1670. In some forms, the end stop is located proximate to the first end 1662 of the pressure chamber 1661. In some forms, a wall is provided at the first end 1662 of the pressure chamber and the wall forms the end stop of the second cavity 1669. In other forms, a projection within the second cavity 1669, proximate to the first end 1662 of the pressure chamber, may form an end stop.

[0212] In some forms, the pressure chamber 1661 comprises a pivotable toggle 1695 that comprises a first end contactable by the second piston 1670, such that the second piston is able to pivot the toggle 1695 between an open position and a closed position.

[0213] The second piston 1670 is slidable longitudinally within the second cavity 1669 in a first direction to reach a first position, and in a second direction to reach a second position. In some forms, the first position is a forwardmost position of the second piston and the second position is a rearward most position of the second piston 1670.

[0214] The second piston 1670 comprises a first end and an opposing second end, the first end facing in the first direction and the second end facing in the second direction.

[0215] In use, as the first piston 1620 slides toward the first position due to the expanding pressure of the combustion gases after a round has been fired, the pressure head 1622 moves past the second gas passage 1680 and allows some of the gases to pass along the second gas passage to the second cavity 1669. Once in the second cavity, the gases push the second piston 1670 toward the first position.

[0216] In some forms, the second piston comprises a collar 1672 projecting from the shaft 1671 of the second piston 1670. The collar 1672 is snugly received within side wall(s) 1669a of the second cavity such that a gap is provided between the shaft 1671 and the side wall(s) 1669a. When the second piston 1670 is in the second position, a gas outlet of the second gas passage 1680 into the second cavity 1669 is located behind the collar 1672. In such an arrangement, as gas enters the second cavity 1669, the gas pushes against the collar 1672 and drives the second piston 1670 to the first position. As the second piston 1670 slides toward the first position, the compression member 1673 of the second piston presses against the second compression element 1690 to compress the second compression element. In some forms, a first end of the piston forms the compression member 1673, as shown in Figures 29 to 33. In other forms, a forward face of the collar 1672 may form the compression member 1673 and the second compression element 1690 may comprise a compression spring that surrounds at least a portion of the second piston shaft 1671 between the collar 1672 and a first end of the shaft 1671 .

[0217] When the second piston 1670 is in the first position, the second piston 1670 compresses the second compression element 1690 between the end stop of the second cavity 1669 and the compression member 1673. In some forms, a forward end of the second piston 1670 forms the compression member 1673 such that the second compression element 1690 is located between the forward end of the second piston 1670 and the end stop of the second cavity 1669.

[0218] As the second piston 1670 reaches the first position, the second piston 1670, the second compression element 1690, or both 1670, 1690 may directly or indirectly contact the toggle 1695 to cause the toggle 1695 to pivot to a closed position in which the toggle 1695 projects behind the pressure head 1622 of the first piston 1620 and presses against a contact surface of the pressure head 1622 to prevent the pressure head and therefore the first piston 1620 from sliding in the second direction, as shown in Figure 30.

[0219] In some forms, the pressure head 1222 may comprise a tapered contact surface at the rear of the pressure head that allows the toggle 1695 to pivot and slide along the contact surface away from the pressure head 1622 when spring tension from the first compression element 1630 overrides the locking action of the toggle 1695. As the toggle 1695 slides away from the pressure head 1622 to disengage with and release the pressure head 1622, the first piston 1620 is caused to slide to the second position as a result of a pulling action by the first compression element 1630.

[0220] After the toggle 1695 disengages from the pressure head 1622, gases have been ejected through the outlet port(s) 1666, and the first piston 1620 slides in the second direction, gases from the second cavity

[0221] 1669 may vent into the first cavity 1668 via the second gas passage 1680 and may also be ejected through the outlet port(s) 1666, releasing pressure in the second cavity 1669. Spring tension in the second compression element 1690 causes the compression element 1690 to expand, pushing the second piston

[0222] 1670 in a second direction toward the second position, as shown in Figures 32 and 33.

[0223] In some forms, the first piston 1620 may be automatically locked in the first position, as described above, and the secondary delay mechanism may comprise a manual reload member that an operator can manually manipulate to cause the toggle 1695 to release the pressure head 1622 in order to allow the first piston 1620 to slide to the second position to release the bolt carrier group 1200 and open the bolt 1220.

[0224] Therefore, by use of spring tension and inertia, a reloading delay may be implemented in all embodiments of the invention. The reloading delay mechanism allows the piston and bolt carrier to be decoupled and the compression element forms an actuator to move the bolt carrier group forward when spring tension in the compression element is released.

[0225] The reloading delay mechanism of the invention therefore causes a reloading delay, but the advantage of the delayed opening of the bolt carrier group from the barrel extension 1350 is that most of the combustion gases are prevented from being ejected through the ejection port and instead are held in the piston cavity or eject through the distal end of the barrel. As such, noise from the reloading mechanism is reduced and the extent of gases released near the operator's face is also reduced.

[0226] In some forms, as shown in Figures 34 to 38, the firearm may be fitted with a suppressor to further muffle the noise created upon firing a round.

[0227] In some forms, a gas block 1800 may be fitted over the forward end of the pressure chamber 1661 to surround the gas outlet port(s) 1666. The gas block 1800 may act to suppress noise from the gas being ejected through the gas outlet port(s) 1666.

[0228] In some forms, the suppressor 1900 comprises a suppressor-initiated reset mechanism to release the first piston from the first position via movement of the suppressor or of components within the suppressor. In some forms, the suppressor-initiated reset mechanism may comprise a Nielsen device 1940, which is commonly used with short recoil firearms, such as pistols. In other forms, the reset mechanism may be similar to a Neilsen device.

[0229] Neilsen devices in recoil operated firearms, such as pistols, are configured to decouple the forward forces of the gases pushing against the suppressor with the normal recoil operated mechanism of the firearm, thereby allowing a pistol to function normally with a suppressor. Some machine guns require Neilsen devices due to the weight of their barrels.

[0230] Therefore, in some forms, as shown in Figure 34, the suppressor 1900 comprises an assembly that may comprise a body 1910, a muffler 1920 located within a hollow of the body 1910, a suppressor spring 1930, and a Neilsen device 1940. After firing a round, the Neilsen device allows the suppressor 1900 to move forward from a neutral position to an extended position momentarily, before spring tension in the Neilsen device 1910 causes the Neilsen device to return to the neutral position.

[0231] In some forms, a suppressor comprising a Neilsen device may be configured to further delay the reloading of the firearm by using the forward movement of the suppressor to momentarily lock the first piston in the first position, until rearward movement of the suppressor releases the first piston.

[0232] For example, as shown in Figures 34 to 38, the reloading delay mechanism may comprise a locking lever 1950 that may pivotably be mounted on the barrel or within a gas block 1800 to move between a locked position and an unlocked position. The mechanism may also comprise a locking lever biasing member that biases the locking lever 1950 to the locked position. The biasing member may comprise any suitable element to bias the locking lever 1950 to the locked position. For example, the biasing member may comprise a spring. In other forms, the biasing member may comprise a weight at a first end of the locking lever 1950 to pivot the locking lever toward the locked position under the force of gravity.

[0233] At a first end, the locking lever 1950 may comprise a tapered toggle surface 1952 that is configured to slide against a sloping rear contact surface 191 1 of the suppressor, such as a rear surface of the Neilsen device 1940. In some forms, as shown in Figures 35 to 38, the pressure chamber 1661 is located above the barrel 1300, the locking lever pivot 1951 is located between the barrel 1300 and the pressure chamber 1661, and the first end of the locking lever 1950 inclines upwardly, toward the front of the firearm 1000 to form a tapered toggle surface 1952 configured to slide across a downwardly inclined rear contact surface 191 1 of the suppressor 1900 the rear contact surface 1911 sloping downwardly in the rearward direction.

[0234] At a second end, the locking lever 1950 comprises a hook or pawl 1953 for engaging with the pressure head 1622 of the first piston 1620. For example, the looking lever hook 1953 may be configured to project into the pressure chamber 1661 , in a locked position, to extend behind the pressure head 1622 of the first piston 1620 to prevent rearward movement of the piston 1620. In some forms, as shown best in Figure 36, the first piston 1620 may comprise a detent 1627 behind the pressure head 1622 and the locking lever hook 1953 may engage with the detent 1627 in the locked position. When the locking lever is moved to the unlocked position, the locking lever 1950 is pivoted away from the pressure chamber 1661 and disengages with the pressure head 1622 of the first piston 1620, thereby allowing the first piston to slide to the second position in order to open the bolt 1220, as shown in Figure 38.

[0235] In use, when a round is ready to be fired, the first piston 1620 is in the second position and is disengaged from the locking lever 1950. At the same time, the toggle surface 1952 of the locking lever rests against the rear contact surface 1911 of the suppressor 1900, which rotates the locking lever to the unlocked position. After a round is fired, the first piston 1620 slides forward to the first position and a portion of combustion gases exiting the muzzle push the suppressor forward, the forward movement of the suppressor being allowed by the suppressor spring 1930. As the suppressor 1900 moves forward to an extended position, the locking lever 1950 loses contact with the rear contact surface 1911 of the suppressor, such that the locking lever biasing member toggles the locking lever 1950 to the locked position, in which the locking lever hook 1953 engages with the first piston 1620 to momentarily hold the first piston in the first position, thereby delaying movement of the first piston 1620 to the second position in order to delay opening of the bolt 1220. As the suppressor 1900 then returns to its neutral position, the rear contact surface 1911 of the suppressor pushes against the toggle surface 1952 of the locking lever, causing the locking lever 1950 to pivot to the unlocked position, thereby disengaging the locking lever 1950 from the first piston 1620 to allow the first piston to slide to the second position in order to open the bolt 1220.

[0236] In other forms, the arrangement may be configured to operate in reverse. For example, the suppressor (1900) may be attached to the muzzle and a spring-loaded rearward operating suppressor piston may be provided to actuate the locking lever (1950) to lock the first piston (1620) in the first position. Therefore, a suppressor comprising a Neilsen device, or a suppressor with a reset mechanism that operates similarto a Nielsen device, may be configured to operate a locking lever to automatically lock and then unlock the first piston in the first position to delay opening of the bolt.

[0237] In some forms, the reloading delay mechanism of the invention may comprise a unitary piston housing in which the actuation chamber and the pressure chamber are located. In another form, the reloading delay mechanism may comprise a two-part piston housing, comprising the actuation chamber, the pressure chamber, and a space in between and through which a substantially central portion of the first piston shaft 1621 extends. An upper receiver may be manufactured with either form of piston housing and then may be retrofit to a lower receiver, by removing and replacing the existing upper receiver.

[0238] The invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, in any or all combinations of two or more of said parts, elements or features.

[0239] Where, in the foregoing description reference has been made to integers or components having known equivalents thereof, those integers are herein incorporated as if individually set forth.

[0240] It should be noted that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the scope of the invention and without diminishing its attendant advantages. It is therefore intended that such changes and modifications be included within the scope of the invention.

Claims

WHAT WE CLAIM IS:

1. A firearm comprising a reloading delay mechanism, wherein the reloading delay mechanism comprises a piston which is moveable within a pressure chamber between a first position and a second position, wherein the piston is movable from the second position to the first position by pressure from combustion gasses communicated to the pressure chamber from a barrel of the firearm, the piston configured to compress a compression element when moving from the second position to the first position, wherein a force exerted by the compressed compression element moves a bolt carrier group of the firearm during a reloading cycle, and wherein the reloading cycle does not begin before the first piston reaches the first position.

2. The firearm of claim 1 , wherein the reloading cycle begins no less than 5 ms after the firearm is fired.

3. The firearm of claim 2, wherein the reloading cycle begins no less than 15 ms after the firearm is fired.

4. The firearm of claim 1 or 2 wherein the reloading cycle begins automatically.

5. The firearm of claim 1 or 2 wherein the reloading cycle is initiated manually.

6. The firearm of any one of claims 1 to 5, wherein the piston moves away from the first position during an ejection phase of the reloading cycle.

7. The firearm of any one of claims 1 to 5 wherein the piston remains in the first position during an ejection phase of the reloading cycle.

8. The firearm of any one of claims 1 to 7, wherein the first compression member moves the piston from the first position to the second position during or after commencement of the reloading cycle.

9. Afi rearm comprising a reloading delay mechanism comprising a piston within a piston housing, wherein combustion gases from a bullet fired by the firearm cause relative movement between the piston and the piston housing, the relative movement causing movement of an action rod which compresses a compression element, wherein a force exerted by thecompressed compression element moves a bolt carrier group of the firearm during a reloading cycle, and wherein the reloading cycle does not begin until at least 5 milliseconds after the firearm is fired.

10. An upper receiver comprising a reloading delay mechanism for a firearm comprising a barrel attached to the upper receiver, wherein the upper receiver comprises a receiver body comprising a hollow interior in which is slidably located a bolt carrier group comprising a bolt carrier, a bolt, and a firing pin; and a buffer system located between the bolt carrier group and a rear end of the receiver body, the buffer system comprising an action spring configured to bias the bolt carrier group towards a forward end of the receiver body, and wherein the reloading system comprises: a piston housing comprising an actuation chamber and a pressure chamber that is sealed from the actuation chamber and that comprises a first gas passage in fluid communication with the barrel, a first elongate piston received within the piston housing and extending between the actuation chamber and the pressure chamber, the first piston comprising a shaft and a pressure head, and also comprising a first compression member that projects laterally from a portion of the shaft located within the actuation chamber, wherein the pressure head is located at or near a first end of the first piston and is snugly received between sidewalls of the pressure chamber and the first piston is slidable longitudinally within the piston housing between a first position and a second position; wherein the actuation chamber comprises an end stop that is distanced from the first compression member; wherein the reloading delay mechanism also comprises: a first compression element that is located within the actuation chamber between the end stop and the first compression member, the first compression element having a compressible length, wherein the first compression element is compressed when the piston moves towards the first position; and a latch capable of adopting a locked position and an unlocked position by movement of the piston, wherein when the first piston slides to the first position, a hook of the latch projects through an opening in one side of the actuation chamber to engage with the bolt carrier group, thereby driving the bolt carrier towards the rear end of the receiver body when the first compression element moves the piston from the first position to the second position, and wherein, when the piston is in the second position, the latch disengages fromthe bolt carrier group, allowing the action spring to move the bolt carrier group towards the forward end of the receiver body.

11. The upper receiver of claim 10, wherein the first compression element comprises a spring.

12. The upper receiver of claim 10 or 1 1, wherein the latch is pivotable and is biased to the locked position by a biasing member.

13. The upper receiver of any one of the preceding claims, wherein the latch is pivotally mounted at or near a second end of the first piston.

14. The upper receiver of claim 13, wherein the first piston comprises a latch mount at the second end of the piston shaft, the latch comprising a hook at or near a first end of the latch and the latch mount comprising a pivot pin and the latch biasing member that presses the latch hook toward the bolt carrier group.

15. The upper receiver of claim 14, wherein the actuation chamber comprises at least one lower guide surface along which the piston is slidable and in which is located an elongate opening, extending along at least a portion of the length of the guide surface, and wherein the latch hook projects through and slides along the elongate opening as the first piston slides within the actuation chamber.

16. The upper receiver of claim 15, wherein the bolt carrier comprises a projecting element comprising a surface inclined toward the first direction that terminates at a transition point to form an abutment surface that projects from a body portion of the bolt carrier, and wherein movement of the first piston in a first direction and toward the first position causes the pivotable latch hook to contact, pivot, and slide across the inclined surface of the bolt carrier, under pressure of the latch biasing member, until the latch hook reaches the transition point of the bolt carrier, at which point the latch hook pivots toward the bolt carrier, under pressure from the biasing member, and hooks against the abutment surface to prevent rearward movement of the bolt carrier group and to thereby prevent reloading of the firearm.

17. The upper receiver of any one of claims 9-16, wherein the pressure chamber is located forward of the actuation chamber.

18. The upper receiver of any one any one of claims 10-17, wherein the actuation chamber and the pressure chamber extend substantially parallel to a longitudinal axis of the barrel.

19. The upper receiver of any one of claims 10-18, wherein the pressure chamber is distanced from the actuation chamber and is supported on the barrel by a support.

20. The upper receiver of any any one of claims 10-19, wherein the reloading delay mechanism further comprises a piston lock that automatically locks the first piston in the first position, holding the first compression element under compression.

21. The upper receiver of claim 20, wherein the piston lock comprises a moveable locking element that engages with the pressure head in a locked position to prevent movement of the pressure head in a second direction and thereby preventing the first piston from sliding to the second position.

22. The upper receiver of claim 20 or 21, further comprising an unlocking member to manually move the piston lock to unlock the piston lock by disengaging the piston lock with the pressure head.

23. The upper receiver of any one of the preceding claims, wherein pressure chamber comprises one or more gas outlet ports located proximate to a forward end of the pressure chamber.

24. The upper receiver of claim 23, wherein the one or more gas outlet ports are located behind the pressure head and proximate to the pressure head when the first piston is in the first position.

25. The upper receiver of any one of claims 10-24, wherein the pressure chamber comprises a first cavity in which a portion of the first piston, including the pressure head, is slidably received, and a second cavity in which a second elongate piston is slidably received, wherein the first gas passage is provided between the barrel and the second cavity and a second gas passage is provided between the second cavity and the first cavity, the second gas passage comprising a gas outlet into the first cavity that is located behind the pressure head when the first piston is in the second position; wherein a second compression element is provided in the second cavity and is located between an end stop of the second cavity and a second compression member of the second piston,wherein a pivotable toggle is provided in the pressure chamber and comprises a first end contactable by the second piston such that the first piston is able to pivot the toggle between an open position and a closed position; wherein the second piston is slidable longitudinally between a first position and a second position and wherein in the first position, the second piston compresses the second compression element between the end stop of the second cavity and the second compression member and the toggle is caused to pivot to a closed position in which the toggle projects behind the pressure head and presses against a contact surface of the pressure head to prevent the pressure head and therefore the first piston from moving in the second direction.

26. The upper receiver of claim 25, wherein the firearm comprises a manual reload member that causes the toggle to release the pressure head to allow the first piston to slide to the second position to release the bolt carrier group and open the bolt.

27. The upper receiver of claim 25, wherein the pressure head comprises a tapered contact surface that allows the toggle to pivot and slide along the contact surface away from the pressure head when spring tension from the first compression element overrides locking action of the toggle, thereby releasing the pressure head and allowing the first piston to slide to the second position.

28. The upper receiver of any one of claims 25 to 27, wherein a forward end of the second piston forms the second compression member such that the second compression element is located between the forward end of the second piston and the end stop of the second cavity.

29. The upper receiver of any one of claims 10-28, comprising a suppressor comprising a Neilsen device and a pivotable locking lever that is moveable between a locked position and an unlocked position, wherein forward movement of the suppressor pivots the locking leverto the locked position to engage with the first piston and hold the first piston in the first position.

30. A firearm comprising an upper receiver as claimed in any one of claims 10-29.31 . The firearm of claim 30, wherein the piston moves to the first position when combustion gasses from firing of the firearm are communicated from the barrel to the pressure chamber via the first gas passage.

32. The firearm of claim 31, wherein the piston reaches the first position no less than 5 ms afterthe firearm is fired.

3. A firearm comprising: an upper receiver comprising a reloading delay mechanism and a barrel attached to the upper receiver, wherein the upper receiver comprises a receiver body comprising a hollow interior in which is slidably located a bolt carrier group comprising a bolt carrier, a bolt, and a firing pin; and a buffer system located between the bolt carrier group and a rear end of the receiver body, the buffer system comprising an action spring configured to bias the bolt carrier group towards a forward end of the receiver body, and wherein the reloading system comprises: a piston housing comprising an actuation chamber and a pressure chamber that is sealed from the actuation chamber and that comprises a first gas passage in fluid communication with the barrel, a first elongate piston received within the piston housing and extending between the actuation chamber and the pressure chamber, the first piston comprising a shaft and a pressure head, and also comprising a first compression member that projects laterally from a portion of the shaft located within the actuation chamber, wherein the pressure head is located at or near a first end of the first piston and is snugly received between sidewalls of the pressure chamber and the first piston is slidable longitudinally within the piston housing between a first position and a second position, wherein the first piston moves to the first position when combustion gasses from firing of the firearm are communicated from the barrel to the pressure chamber via the first gas passage; and; wherein the actuation chamber comprises an end stop that is distanced from the first compression member; wherein the reloading delay mechanism also comprises: a first compression element that is located within the actuation chamber between the end stop and the first compression member, the first compression element having a compressible length, wherein the first compression element is compressed when the piston moves towards the first position; and a latch capable of adopting a locked position and an unlocked position by movement of the piston, wherein when the first piston slides to the first position, a hook of the latch projects through an opening in one side of the actuation chamber to engage with the bolt carrier group to begin a reloading cycle, wherein the reloading cycle begins no less than 5 ms after the firearm is fired.

34. The firearm of claim 33, wherein during the reloading cycle, the bolt carrier moves towards the rear end of the receiver body when the first compression element moves the piston from the first position to the second position, and when the piston is in the second position, the latch disengages from the bolt carrier group, allowing the action spring to move the bolt carrier group towards the forward end of the receiver body.

35. The firearm of claim 33 or 34, wherein the pressure chamber comprises one or more gas outlet ports, and wherein the gas outlet ports are in fluid communication with the first gas passage, via the pressure chamber, when the piston is in the first position.

36. The firearm of claim 35, wherein the one or more gas outlet ports are located proximate to the pressure head when the first piston is in the first position.

37. A firearm comprising: an upper receiver comprising a reloading delay mechanism and a barrel attached to the upper receiver, wherein the upper receiver comprises a receiver body comprising a hollow interior in which is slidably located a bolt carrier group comprising a bolt carrier, a bolt, and a firing pin; and a buffer system located between the bolt carrier group and a rear end of the receiver body, the buffer system comprising an action spring configured to bias the bolt carrier group towards a forward end of the receiver body, and wherein the reloading system comprises: a piston housing comprising an actuation chamber and a pressure chamber that is sealed from the actuation chamber and that comprises a first gas passage in fluid communication with the barrel, a first elongate piston received within the piston housing and extending between the actuation chamber and the pressure chamber, the first piston comprising a shaft and a pressure head, and also comprising a first compression member that projects laterally from a portion of the shaft, wherein the pressure head is located at or near a first end of the first piston and is snugly received between sidewalls of the pressure chamber and the first piston is slidable longitudinally within the piston housing between a first position and a second position, wherein the first piston moves to the first position when combustion gasses from firing of the firearm are communicated from the barrel to the pressure chamber via the first gas passage; and; wherein the actuation chamber comprises a first compression element that is compressed by the compression member when the piston moves to the first position,wherein, a force exerted by the compressed compression element moves the bolt carrier group rearward during a reloading cycle, and wherein the reloading cycle does not begin before the first piston reaches the first position.

38. The firearm of claim 37, wherein the reloading cycle begins no less than 5 ms after the firearm is fired.

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