Captured spring assembly for firearm
Patent Information
- Application Number
- NZ835473
- Authority / Receiving Office
- NZ · NZ
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2024-02-14
- Filing Date
- 2025-01-16
- Publication Date
- 2025-08-21
AI Technical Summary
Traditional captured spring assemblies in AR-type rifles face issues with uncontrolled exit during disassembly and maintenance, and the buffer retaining pin gets stuck in radial grooves, making removal difficult.
The captured spring assembly features grooves or tangential cuts on the outer surface of weight pieces, allowing the buffer retaining pin to be positioned away from the groove area for easy removal, and connecting weight pieces to prevent individual rotation, facilitated by through holes and pins for simultaneous adjustment.
Ensures easy and controlled removal of the captured spring assembly from the buffer tube, minimizing pin resistance and protecting the buffer tube from damage during use.
Smart Images
Figure 1_ABST
Abstract
Description
[0001] CAPTURED SPRING ASSEMBLY FOR FIREARM
[0002] Technical field
[0003] The present invention relates to a captured spring assembly for a firearm, and especially for an AR-type assault rifle. More specifically the present invention relates to the form and shaping of the movable buffer of the captured spring assembly.
[0004] Backqround
[0005] A captured spring assembly is typically used in AR-type rifles to replace the traditional buffer and buffer spring assembly for returning the bolt carrier after firing of the rifle.
[0006] An example of a captured spring assembly is disclosed for example in patent publication US 8,800,424 B2. The captured spring assembly typically comprises a movable buffer movable along a rod, a spring arranged around the rod resisting the movement of the buffer, and a spring stop at the opposite end of the rod in relation to the buffer, as well as limit element preventing the buffer to be pushed outside on the rod by the spring.
[0007] The captured spring assembly, among other advantages, eliminates an occasional noise problem of the traditional buffer and buffer spring assembly caused by the spring rubbing the inner surface of the buffer tube when the firearm is fired. Further, the captured spring assembly also provides constrained movement of the buffer and a compact buffer unit comprising all the required functional parts, which is easy to handle especially when dismantling and reassembling AR-type rifles.
[0008] The buffer part of the captured spring assembly is formed of a plurality of cylindrical weight pieces arranged adjacently on the rod of the assembly. The amount, material and weight of these weight pieces may vary so the weight of the buffer part formed from these weight pieces can be adjusted to be suitable for the selected type of the captured spring assembly.
[0009] Between the adjacent weight pieces forming the buffer part there is radial grooves. These radial grooves in the buffer part impede the removal of the captured spring assembly from the buffer tube of the firearm, since an upper end of a spring loaded buffer retaining pin, which keeps the captured spring assembly inside the buffer tube, tends to get stuck in the grooves.
[0010] Summary
[0011] The present invention provides a novel solution for overcoming the above mentioned problem with the traditional captured spring assemblies. With the present invention uncontrolled exit of the captured spring assembly from the buffer during disassembling and maintenance of the firearm can be eliminated, while maintaining easy and simple removal of the captured spring assembly from the buffer tube when necessary.
[0012] In the present invention at least one groove or tangential cut extending in the longitudinal direction of the captured spring assembly is formed on the outer surface of the weight pieces forming the buffer part. By locating the groove or tangential cut at the area of the buffer retaining pin, the resistance of the buffer retainer pin when removing the buffer part of the captured spring assembly from the buffer tube can be minimized. Further, by connecting the individual weight pieces of the buffer part to each other so that the individual weight pieces cannot rotate around the rod of the captured spring assembly individually, the obtained advantage can be increased.
[0013] With the present invention the said groove or cut can also be rotated away from the area of the buffer retaining pin when the captured spring assembly is located inside the buffer tube, which allows the use of the buffer retaining pin for keeping the captured spring assembly inside the buffer tube.
[0014] The captured spring assembly of the invention for a firearm comprises a buffer part arranged movably on and around a rod, a spring, a limit element arranged at one end of the rod for preventing the buffer part to be pushed out from the rod, and a spring stop at the second end of the rod, wherein the rod extends inside the spring and the spring arranged between the spring stop and the buffer part to resist the movement of the buffer part towards the spring stop, wherein the buffer part comprises at least two weight pieces arranged adjacently on the rod in the length direction of the rod, and wherein the weight pieces comprise at least one groove or tangential cut on the outer surface of the weight pieces, which groove or cut extends in the longitudinal direction of the rod through the weight pieces.
[0015] In an embodiment of the captured spring assembly of the invention the weight pieces are connected to each other to prevent the individual weigh pieces to rotate around the rod individually. In this embodiment the connection between the weight pieces preferably comprise through holes in each of the weight pieces, and a pin arranged in the through holes, which pin connects each of the weight pieces.
[0016] In an embodiment of the captured spring assembly of the invention the spring stop is formed from one or more parts made of a material which is compressible and / or deformable. This allows deformation of the spring stop when the buffer part impacts the spring stop during use, and return to original, or substantially original shape after receiving the impact. This protects the buffer tube from damage during the use.
[0017] More precisely the features defining a captured spring assembly in accordance with the present invention are presented in claim 1 . Dependent claims present advantageous features and embodiments of the invention.
[0018] Brief description of the drawings
[0019] Exemplifying embodiment of the invention and its advantages are explained in greater detail below in the sense of example and with reference to accompanying drawings, where
[0020] Figure 1 shows schematically a lower receiver of a firearm with a buffer tube connected to it,
[0021] Figure 2 shows schematically a cross-section of the buffer tube of figure 1 ,
[0022] Figure 3 shows schematically an embodiment of a captured spring assembly in accordance with the present invention inside the buffer tube from the open end of the buffer tube,
[0023] Figure 4 shows schematically the embodiment of figure 3, and
[0024] Figure 5 shows schematically an alternative embodiment of a captured spring assembly in accordance with the present invention inside the buffer tube from the open end of the buffer tube. Detailed description
[0025] Figure 1 shows a lower receiver 1 of an AR-type firearm, to which lower receiver a buffer tube 2 is connected.
[0026] As shown in figure 2, inside the buffer tube 2 is located a captured spring assembly 3, which is used for returning the bolt carrier of the firearm after firing of the firearm. The captured spring assembly 3 is retained inside the buffer tube with a buffer retainer pin 10 fixed to the lower receiver 1 .
[0027] The captured spring assembly 3 comprises a buffer part 4 arranged movably on and around a rod 5, a spring 6, a limit element (not shown) arranged at one end of the rod for preventing the buffer part to be pushed out from the rod, and a spring stop 7 at the second end of the rod. The spring 6 is arranged around the rod 5 between the spring stop 7 and the buffer part 4 to resist the movement of the buffer part towards the spring stop and for returning the buffer part to the first end of the rod after the firearm is fired.
[0028] The spring stop 7 preferably comprises one or more pieces of compressible and / or deformable material, so that the impact of the buffer part 4 can be at least partially absorbed by the spring stop by compression and deformation. This protects the buffer tube from damage during use.
[0029] The buffer part 4 comprises and is formed of a plurality of separate weigh pieces 4a-4d, which can be changed to adjust the operation of the captured spring assembly.
[0030] Figures 3 and 4 illustrate an embodiment of the captured spring assembly 3 of the invention.
[0031] As can be seen from the figures 3 and 4, three cuts 8a-8c are formed on the outer surface of the weight pieces 4a-4d forming the buffer part 4 of the captured spring assembly 3. When the captured spring assembly 3 is removed from the buffer tube 2, one of these cuts 8a-8c is rotated at the area of the buffer retainer pin 10 (as shown in figure 3), which allows the buffer part 4 of the captured spring assembly to be withdrawn from the buffer tube without pressing the buffer retainer pin downwards. In the embodiment of the figures, the weigh pieces 4a-4d comprise a through hole 9, which through hole extends through the weight pieces. In the through hole 9 is inserted a suitable pin or screw (not shown), which connects all of the weight pieces 4a-4d, so that when the first weight piece 4a is rotated inside the buffer tube 2, all of the weight pieces rotate simultaneously. This way the buffer part is easily positioned with single adjustment turning without the need for individually turning each of the weigh pieces 4a-4d to position one of the cuts 8a-8c to the area of the buffer retainer pin when withdrawing the buffer part from the buffer tube.
[0032] Figure 5 shows an alternative embodiment of a captured spring assembly of the present invention. This embodiment corresponds to the embodiment shown in figures 3 and 4, but in this embodiment the cuts 8a-8c are replaced with a groove 11 . Similarly as with the cuts 8a-8c, the cut 11 extends through all of the weigh pieces 4a-4d. During use of the groove 11 is rotated away from the location of the buffer retainer pin 10, and when the captured spring assembly 3 is removed from the buffer tube 2, the groove is turned at the location of the buffer retainer pin, after which the captured spring assembly is easy to withdraw from the buffer tube.
[0033] The specific exemplifying embodiment of the invention shown in the figure and discussed above should not be construed as limiting. A person skilled in the art can amend and modify the embodiment described in many evident ways within the scope of the attached claims. Thus, the invention is not limited merely to the embodiment described above.
Claims
Claims:1 . Captured spring assembly (3) for a firearm, which assembly comprises a buffer part (4) arranged movably on and around a rod (5), a spring (6), a limit element arranged at one end of the rod for preventing the buffer part to be pushed out from the rod, and a spring stop (7) at the second end of the rod, wherein the rod extends inside the spring and the spring arranged between the spring stop and the buffer part to resist the movement of the buffer part towards the spring stop, and wherein the buffer part comprises at least two weight (4a-4d) pieces arranged adjacently on the rod in the length direction of the rod, characterized in that the weight pieces (4a-4d) comprise at least one groove (11 ) or tangential cut (8a-8c) on the outer surface of the weight pieces, which groove or cut extends in the longitudinal direction of the rod (5) through the weight pieces.
2. Captured spring assembly (3) of claim 1 , wherein the weight pieces (4a- 4d) are connected to each other to prevent the individual weigh pieces to rotate around the rod (5) individually.
3. Captured spring assembly (3) of claim 2, wherein the connection between the weight pieces (4a-4d) comprise through holes (9) in each of the weight pieces, and a pin arranged in the through holes, which pin connects each of the weight pieces.
4. Captured spring assembly (3) of any of claims 1 -3, wherein the spring stop (7) preferably comprises one or more pieces of compressible and / or deformable material.
5. Firearm, which firearm comprises a lower receiver (1 ) with a buffer tube (2), and a captured spring assembly (3) of any of the previous claims arranged inside the buffer tube.