Bullet, method and apparatus for making bullet, and cartridge

Abstract

In the presented solution, a body part (2) of a bullet (1) is made from material that is more resistant to deformation than lead. The bullet (1) includes a tapered front section (4) and a cylindrical section (3) that defines its outer diameter. The cylindrical section (3) includes on its outer surface grooves (8) in the longitudinal direction of the bullet (1). The grooves (8) reduce friction between the outer surface of the bullet (1) and the rifling of the barrel of the weapon and, thus, decrease heating of the bullet (1) and the barrel and enable the rifling of the barrel of the weapon to displace material from the outer diameter of the bullet (1) into the grooves (8).

Description

[0001] Bullet, method and apparatus for making bullet, and cartridge

[0002] Background of the invention

[0003] The invention relates to a bullet and particularly to a bullet used in hunting or a precision bullet used in shooting sports.

[0004] Traditionally, bullets have been manufactured of lead such that the bul- let either totally consists of lead or an essential part of the bullet consists of lead. Due to environmental concerns, there are efforts to eliminate the use of lead and, in some contexts, the use of lead is even totally banned. Lead has high density and quite high malleability, which makes it easily formable into bullets for various needs. A challenge in the manufacturing of a bullet from some other material than lead is how to cost-effectively produce bullets that are precise and meet the re- quirements of each target of use.

[0005] Brief description of the invention

[0006] The object of the invention is thus to develop a novel type of a bullet and cartridge and a method and apparatus for manufacturing the bullet. The solution according to the invention is characterised by what is disclosed in the independent claims. Some embodiments of the invention are disclosed in the dependent claims.

[0007] In the presented solution, the body part of the bullet is made from ma- terial that is more resistant to deformation than lead. The bullet includes a tapered front section and a cylindrical section that defines its outer diameter. On its outer surface, the cylindrical section includes grooves in the longitudinal direction of the bullet, that is, substantially parallel with the longitudinal axis of the bullet. The grooves reduce friction between the outer surface of the bullet and the rifling of the barrel of the weapon and, thus, decrease heating of the bullet and the barrel and enable the rifling of the barrel of the weapon to displace material from the outer diameter of the bullet into the grooves. Such a bullet is precise and it can be manu- factured in a simple, reliable and effective manner. Furthermore, the grooves de- crease adherence of the material of the bullet to the rifling and surface of the barrel of the weapon, that is, e.g. if the bullet is made of copper, the grooves reduce copper fouling of the barrel of the weapon. Additionally, the grooves help to maintain the shape of the bullet extremely well after firing during the barrel phase. In other words, the bullet does not substantially become deformed when going through the barrel but its shape remains substantially flawless, that is, accurate of shape and dimensions during the barrel phase. According to an embodiment, the length of at least some of the grooves in the cylindrical section is at least 10% of the length of the cylindrical section. Ac- cording to an embodiment, the length of at least some of the grooves in the cylin- drical section is at least 30% of the length of the cylindrical section and, according to a further embodiment, the length of at least some grooves in the cylindrical sec- tion is at least 40% of the length of the cylindrical section. The longer the grooves are, the better they provide the bullet with the preferred characteristics described above. Due to the longitudinal grooves, the precision of the bullet is thus quite good.

[0008] According to an embodiment, the length of at least some of the grooves in the cylindrical section is less than 80% of the length of the cylindrical section. According to an embodiment, the grooves start in the cylindrical section so far from the bottom of the bullet that the groove does not extend to the whole length of the neck of a case. When the grooves are not too long, their formation e.g. by compres- sion is possible without excessive need of force. Additionally, the bullet does not become deformed in the wrong place. When there is no groove on the whole length of the neck of the case, the cartridge can be formed tight, and gunpowder inside the cartridge is not exposed to environmental conditions.

[0009] According to an embodiment, at least some of the grooves extend to the area of the tapered front section. Such a bullet is cost-effective to form from the technical viewpoint of manufacturing. The bullet can be manufactured by utilising e.g. a compressor making a motion in the direction of the longitudinal axis of the bullet. Furthermore, the grooves in the area of the tapered front section can affect the expansion of the front section of the bullet. For example, the grooves in the front section of a hollow-point bullet can facilitate the opening and expansion of the front section of the bullet.

[0010] According to an embodiment, the sum of the groove widths is 10-50% of the length of the perimeter of the outer diameter of the cylindrical section. When there are sufficiently of grooves in relation to the perimeter of the outer diameter of the bullet, improvements are provided in the characteristics of the bullet. For example, the ballistics of the bullet remains excellent. When there are not too many of the grooves and / or they are not too large, the manufacture of the bullet is easy and simple.

[0011] According to an embodiment, the depth of at least some of the grooves equals at least the height of the rifling of the barrel of the weapon. Hence, it is en- sured that the material of the bullet displaced by the rifling of the barrel of the weapon has space to move between the bullet and the barrel of the weapon. According to an embodiment, the number of the grooves is at least six. When there is a sufficient number of grooves around the bullet, the grooves do not need to be deep and / or wide and, still, e.g. the material of the bullet displaced by the rifling of the barrel of the weapon has space to move between the bullet and the barrel of the weapon. All in all, the bullet does not substantially become de- formed when going through the barrel but its shape remains substantially flawless, that is, accurate of shape and dimensions during the barrel phase, whereby the op- eration of the bullet is good. On the other hand, longitudinal grooves have less harmful effects on the ballistics than e.g. cross-directional grooves, whereby the ballistics of the bullet can be optimised. As a whole, the landing of the bullet can be achieved excellent.

[0012] According to an embodiment, the bullet is manufactured such that a bul- let blank is cut from a wire or rod made of material more resistant to deformation than lead. The bullet blank is shaped into a bullet. Grooves in the longitudinal di- rection of the bullet, that is, substantially parallel with the longitudinal axis of the bullet, are formed on the outer surface of the cylindrical section of the bullet defin- ing its outer diameter. According to an embodiment, the bullet is manufactured in this manner by a phase compression machine making a motion in the direction of the longitudinal axis of the bullet. The bullet diameter is calibrated. Such a manu- facturing method of the bullet is quick and effective. Additionally, there is no need to remove material from the bullet blank, whereby it does not go to waste. The lon- gitudinal grooves are also formed in a simple and reliable way.

[0013] Brief description of the drawings

[0014] The invention will now be described in closer detail in connection with some embodiments and with reference to the accompanying drawings, in which:

[0015] Figure 1 is a schematic side view of a bullet;

[0016] Figure 2 is a schematic cross section of the bullet of Figure 1 sectioned along line B-B of Figure 1;

[0017] Figure 3 shows a block diagram which describes a method for manufac- turing a bullet;

[0018] Figure 4a is a schematic cross section of a blank of the body part of a bullet;

[0019] Figure 4b is a schematic cross section of a compressed blank of a body part of a bullet;

[0020] Figure 4c is a schematic cross section of a blank of the body part of a bullet when tapering has been done to the blank; Figure 4d is a schematic cross section of a bullet;

[0021] Figure 4e is a schematic side view of the bullet of Figure 4d;

[0022] Figure 5 is a schematic view of an apparatus for manufacturing a bullet;

[0023] Figure 6 is a schematic cross-sectional side view of a grooving device, and

[0024] Figure 7 is a schematic view of a front section of the grooving device of Figure 6 seen from the direction of a rear section of the grooving device.

[0025] Detailed description of the invention

[0026] Figure 1 is a side view of a bullet 1. The bullet 1 includes a body part 2. The body part 2 consists of one material which material is more resistant to defor- mation than lead. The body part 2 can be of e.g. metal, such as copper. Furthermore, the body part 2 can be of e.g. some other metal or copper-based alloy, such as brass or bronze. Additionally, the body part 2 can be of e.g. some other alloy or metal- polymer composite.

[0027] The body part 2 includes a cylindrical section 3. The cylindrical section 3 defines an outer diameter of the bullet 1. The bullet 1 includes a tapered front section 4 in front of the cylindrical section 3. In the embodiment of Figure 1, the bullet 1 includes an endpiece 5 which is formed separately from the body part 2 and fitted into connection with the front section of the body part 2. In this case, the tapered front section 4 of the bullet 1 is formed by a tapering section extending forward from the cylindrical section 3 of the body part 2 and the endpiece 5 in question. It is also possible to have an embodiment which does not include an end- piece formed separately from the body part 2, but the body part 2 also forms the frontmost point of the bullet 1. By means of the endpiece 5, it is possible to improve the ballistic properties of the bullet.

[0028] In the body part 2, there can be a rear part 6 at the back of the cylindrical section 3, as shown in Figure 1. The shape of the rear part 6 can be that of a back- wards tapering truncated cone.

[0029] The rearmost point of the bullet 1 is a bottom 7. In the embodiment of Figure 1, the bottom 7 is straight i.e. even. If preferred, the 7 can also be of some other shape.

[0030] The shape of the rear part 6 can be something else than that of a back- wards tapering truncated cone. For example, the cylindrical section 3 can also con- tinue with the same shape until the bottom 7 or at least to its vicinity. Then, a bevel can be made to the rear corner of the bullet 1. The bevel or the backwards tapering truncated cone shape facilitates the setting of the bullet 1 to the cartridge. It is also possible to make a bevel to the rear corner of the bullet 1 in such a case that the rear part 6 is of the shape of a backwards tapering truncated cone. Furthermore, the rear part 6 can be formed of a cone at two or three or even more corners.

[0031] The longitudinal axis of the bullet 1 is illustrated in Figure 1 by designa- tion A. At the same time, the longitudinal axis A is the centre axis of the bullet 1. On its outer surface, the cylindrical section 3 includes grooves 8 in the longitudinal direction of the bullet 1, that is, substantially parallel with the longitudinal axis A of the bullet 1. The grooves 8 are substantially parallel with the longitudinal axis A of the bullet 1 e.g. when the direction of the grooves 8 differs less than 5 degrees from the direction of the longitudinal axis A or e.g. when the direction of the grooves 8 differs less than 2 degrees from the direction of the longitudinal axis A or e.g. when the direction of the grooves 8 differs no more than a manufacturing tolerance from the direction of the longitudinal axis A.

[0032] A total length LI of the bullet 1 can be e.g. 15-65 mm. A length L2 of the cylindrical section 3 can be e.g. 25-50% of the bullet length LI. A length of the groove 8 is designated by L3. The length L3 of the groove can be e.g. 5-50% of the bullet length LI. The groove 8 can be located in the cylindrical section 3 for its total length L3 or the groove 8 can be located e.g. partially in the cylindrical section 3 and partially in the distance of the tapered front section 4, as shown in Figure 1.

[0033] According to an embodiment, the length of at least some of the grooves 8 in the cylindrical section L4 is at least 10% of the length L2 of the cylindrical sec- tion. According to an embodiment, the length of at least some of the grooves 8 in the cylindrical section L4 is at least 30% of the length L2 of the cylindrical section and, according to a further embodiment, the length of at least some grooves 8 in the cylindrical section L4 is at least 40% of the length L2 of the cylindrical section.

[0034] According to an embodiment, the length of at least some of the grooves 8 in the cylindrical section L4 is less than 60% of the length L2 of the cylindrical section. According to another embodiment, the length of at least some of the grooves 8 in the cylindrical section L4 is less than 80% of the length L2 of the cy- lindrical section. In the embodiment of Figure 1, the grooves 8 start in the cylindri- cal section 3 so far from the bottom 7 of the bullet 1 that there is no groove 8 in the whole length of the neck of a case 9 in the cartridge. Figure 1 schematically shows a part of the case 9 of the cartridge on the side of the neck part of the case. When no groove 8 extends to the whole length of the neck of the case 9, the cartridge can be formed tight, and gunpowder inside the cartridge is not exposed to environmen- tal conditions and, when shooting, the pressure cannot discharge past the bullet. According to an embodiment, there is no groove 8 at the point of the neck of the case 9 at least on the distance of 1 mm. According to another embodiment, there is no groove 8 at the point of the neck of the case 9 at least on the distance of 2 mm. In addition to the bullet 1 and the case 9, the cartridge includes e.g. a primer and gunpowder, but they have been omitted from the figures for clarity.

[0035] In the embodiment of Figure 1, at least some of the grooves 8 extend to the area of the tapered front section 4. Such grooves 8 are easy to manufacture by a pressing device making a motion in the direction of the longitudinal axis A of the bullet 1. In this case, there is a protrusion in the tool of the pressing device which makes the groove 8 to the bullet 1. The bottom of the groove 8 can be at the same distance from the centre axis of the bullet 1 for the whole distance of the groove 8. In the area of the tapered front section 4, the depth of the groove 8 is first zero seen from the end of the bullet 1 and the groove deepens in the distance of the tapered front section 4. The depth of the groove 8 when the tapered front section 4 ends equals the depth of the groove 8 in the cylindrical section 3. In the cylindrical sec- tion 3, the depth of the groove 8 can remain unchanged. Furthermore, it is also pos- sible to have such an embodiment where the depth of the groove 8 in its end, that is, at the end on the side of the rear part 6, decreases. Then, the protrusion of the tool, which is used to press the grooves, can at the start include a bevelled shape, which makes the grooving easier to make when compared with the start of the pro- trusion in the tool being instantly a sharp edge.

[0036] On the other hand, the distance where the grooves 8 extend in the area of the tapered front section 4 is dependent on the depth of the grooves 8, that is, on how close to the centre axis of the bullet the protrusions of the pressing device ex- tend. Similarly, the distance where the grooves 8 extend in the area of the tapered front section 4 is dependent on how steeply the front section 4 tapers. According to an embodiment, the grooves 8 extend to the whole distance of the tapered front section 4.

[0037] All of the grooves 8 can have equal length. It is also possible to have such an embodiment that the grooves 8 are of different lengths.

[0038] A largest outer diameter DI of the bullet 1 can be e.g. 5-10 mm. Then, the perimeter of the outer diameter of the cylindrical section 3 can be about 15-30 mm. In the embodiment of Figure 1, there are 12 grooves 8 around the bullet 1. According to an embodiment, the number of the grooves 8 is at least six. According to an embodiment, the number of the grooves 8 is 15 or less. If the number of the grooves 8 is too large, it can complicate the manufacture of the bullet 1. The width of the groove 8 can be e.g. 0.2-1 mm The grooves 8 can be of the same width. It is also possible to have such an embodiment where the grooves 8 are of different widths.

[0039] The width of the grooves 8 and their number affect the sum of the widths of the grooves 8 at the same cross-section point. According to an embodi- ment, the sum of the groove widths is 10-50% of the length of the perimeter of the outer diameter of the cylindrical section. The percentage in question also describes the fact how much the grooves 8 at the point in question decrease the friction area.

[0040] In this context, the width of the groove 8 refers to the width of the groove 8 on the outer surface of the bullet. The shape of the cross section of the groove 8 can be rectangular, whereby the groove 8 is equally wide from its bottom as from its upper part. Furthermore, the cross section of the groove 8 can be such that the walls are sloping, whereby the groove 8 is narrower of its bottom than its upper part. Additionally, the cross section of the groove 8 can be such that the walls of the groove 8 are curved. For the part of the cross section, the bottom of the groove 8 can be e.g. straight or curved. The cross section of the groove 8 can also be totally rounded. Furthermore, the cross section of the groove 8 can be of some other shape than those described above.

[0041] The depth of the groove 8 in the cylindrical section 3 can be e.g. 0.05- 0.3 mm. The grooves 8 can be equal of their depth. It is also possible to have such an embodiment where the grooves 8 are of different depths.

[0042] The bullets 1 are manufactured for a weapon of a specific calibre. Typi- cally, a weapon of a certain calibre has riflings of a specific height. Therefore, the height of the rifling of the barrel of the weapon can be considered when determin- ing the depths of the grooves 8. According to an embodiment, the depth of at least some of the grooves 8 equals at least the height of the rifling of the barrel of the weapon.

[0043] In the embodiment of Figure 1, the bullet 1 includes an endpiece 5 which is formed separately from the body part 2. A cavity is formed at the front end of the body part 2, whereby the endpiece 5 is fitted partially inside the cavity. The end- piece 5 can be fitted to fill the cavity totally or, then, the endpiece 5 can be fitted to fill the cavity partially, whereby an empty part remains in the middle of the bullet behind the endpiece.

[0044] A precision bullet used in shooting sports can be formed either without an endpiece or it can be provided with an endpiece. If the precision bullet is provided with the endpiece, the endpiece is then typically fitted to fill the cavity in full or almost full.

[0045] When a hunting bullet is provided with an endpiece 5, the endpiece 5 is then typically fitted to fill the cavity partially, whereby an empty part Ila remains in the middle of the bullet behind the endpiece 5. Such a solution is illustrated in Figure 4d. When hitting a target, the endpiece 5 penetrates the empty part Ila of the cavity at the front end of the body part 2 and makes the body part 2 of the bullet 1 expand controllably. However, the body part 2 remains one piece.

[0046] The material of the endpiece 5 can be e.g. polymer material, such as plastic. An example of a suitable plastic material is polyacetal POM. According to an embodiment, the endpiece 5 is of biodegradable polymer material. Furthermore, the material of the endpiece 5 can be e.g. aluminium or copper or steel or an alloy of different materials.

[0047] The deceleration of the bullet 1 is described by a ballistic coefficient (BC). The ballistic coefficient describes the deceleration of a bullet during flight compared with a standard bullet. In tests performed, it was surprisingly observed that the ballistic coefficient of the bullet 1 provided with the longitudinal grooves 8 is of the same rating with a bullet without grooves and better than that of a bullet provided with a transverse groove or transverse grooves.

[0048] According to an embodiment, the bullet is manufactured such that a bul- let blank is cut from a wire or rod made of material more resistant to deformation than lead. The bullet blank is shaped into a bullet. Grooves in the longitudinal di- rection of the bullet, that is, substantially parallel with the longitudinal axis of the bullet, are formed on the outer surface of the cylindrical section of the bullet defin- ing its outer diameter. According to an embodiment, the longitudinal grooves are formed in the bullet by a phase compression machine making a motion in the di- rection of the longitudinal axis of the bullet. The bullet diameter is calibrated. Such a manufacturing method of the bullet is quick and effective. Additionally, there is no need to remove material from the bullet blank, whereby it does not go to waste. The longitudinal grooves are also formed in a simple and reliable way.

[0049] Figure 3 shows the steps of the manufacturing method of the bullet in an extremely simplified manner. In a first step 101, a bullet blank is cut from a metal wire or a metal rod. Such a blank 10 of the body part of the bullet is shown in Figure 4a.

[0050] In a second step 102, the bullet blank 10 is worked by compression. When working the bullet blank 10 by compression, it is possible to form a cavity 11 to its front section. During the forming of the cavity 11, it is also possible e.g. to shape the rear part of the bullet to the shape of a backwards tapering truncated cone. There can be one or more of compression steps 102. The bullet blank shaped by compression is shown in Figure 4b.

[0051] In step 103, a point radius is shaped to the front section of the blank bullet 10. In this case, when shaping the bullet, a tapered front section is formed to it, that is, a point is formed to the bullet. The bullet with the point is illustrated in Figure 4c.

[0052] After the forming of the point, in step 104, an endpiece is installed in place. The endpiece is installed to the formed end cavity.

[0053] In step 105, grooves in the longitudinal direction of the bullet are formed on the outer surface of the cylindrical section defining the outer diameter. According to an embodiment, the longitudinal grooves are formed in the bullet by a phase compression machine making a motion in the direction of the longitudinal axis of the bullet. At the same time with the forming of the longitudinal grooves, it is possible to set an endpiece to the cavity formed in the front section of the body part. The endpiece can also be fitted in place before forming the longitudinal grooves or after forming them. On the other hand, the longitudinal grooves can be formed already in step 102 or 103 in an embodiment. Then, the longitudinal grooves can be reasonably simply formed to the tapering end section even until the endpiece.

[0054] In a next step 106, the diameter of the bullet is calibrated. When cali- brating, it is ensured that the outer diameter of the bullet is of the size of the pre- ferred calibre. When calibrating, the outer diameter and roundness of the bullet are specified and standardised. The calibration can be performed in the last step of the manufacturing steps or calibration can be performed earlier, such as before in- stalling the endpiece. A bullet manufactured by the described method is shown in Figures 4d and 4e. Figure 5 shows an apparatus for manufacturing a bullet. The ap- paratus includes a cutting device 21. The cutting device 21 is used for cutting bullet blanks from a wire or bar. The bullet blanks are transferred from the cutting device 21 to a compression device 22. The transfer of the bullet blanks from one device of the apparatus to another is illustrated by arrows in Figure 5. The bullet blanks are transferred from one device to another e.g. manually or there can be a conveyor between the devices or, when using e.g. a multiphase compression apparatus, one device applies many measures to the blank. There can be one or more of the compression devices 22. The compres- sion device 22 can include a pressing punch which forms a cavity inside the front end of the blank of the body part of the bullet during compression. The compres- sion device 22 can further include means for shaping the bullet e.g. such that the end part 6 of the bullet can be shaped to a backwards tapering truncated cone.

[0055] From the compression device 22, the bullet blanks are transferred to a point-forming device 23. The point-forming device 23 forms a tapered front section to the bullet. The compression devices and the point-forming device can be to- gether called as devices to shape the bullet.

[0056] From the point-forming device 23, the bullet blanks are transferred to an endpiece installation device 24. The endpiece installation device 24 fits an end- piece in place to the bullet blank.

[0057] After the endpiece installation device 24, the bullet blanks are trans- ferred to a groove-forming device 25. The groove-forming device 25 includes means for forming grooves in the longitudinal direction of the bullet to the cylin- drical section defining the outer diameter of the bullet. The groove-forming device 25 can also include means for fitting an endpiece to the cavity formed at the end of the bullet blank, whereby there is no need for a separate endpiece installation de- vice 24.

[0058] After the groove-forming device 25, there is a calibration device 26. The specification and standardisation of the outer diameter and roundness of the bullet are performed in the calibration device 26.

[0059] Figures 6 and 7 illustrate a groove-forming device 25. In this case, the groove-forming device 25 includes a rear part 27 to which the bullet blank can be fitted. The rear part 27 of the groove-forming device 25 is configured to move in relation to a front part 28 of the groove-forming device 25 in the longitudinal di- rection of the bullet in a manner shown by arrows. The groove-forming device 25 can be implemented such that the front part 28 is configured stationary and the rear part 27 moves. The groove-forming device 25 can also be implemented such that the rear part 27 is stationary and the front part 28 moves or such that both the front part 28 and the read part 27 move.

[0060] Protrusions 29 are formed to the front part 28 on the inner surface of its body. The height of the protrusions 29 is dimensioned such that they extend in the radial direction of the bullet closer to the centre axis than the distance of the outer surface of the bullet in the cylindrical section of the bullet. In this case, when the rear part 27 of the groove-forming device 25 moves in relation to the front part 28 in the longitudinal direction of the bullet, grooves in the longitudinal direction of the bullet are formed on the outer surface of the bullet.

[0061] The groove-forming device 25 can also include means for setting the endpiece 5 partially to the cavity 11 formed in the front section of the bullet blank. The endpiece 5 can settle to the cavity by a slight press fit. For clarity, Figure 6 does not show the bullet blank but, instead, the endpiece 5 is illustrated in Figure 6.

[0062] Figure 6 further schematically shows a hole 30 for a removal pin. The removal pin pushes the grooved bullet out of the groove-forming device 25.

[0063] The groove-forming device 25 can also be formed such that, when form- ing longitudinal grooves, the front part and the rear part are stationary in relation to each other, and the grooves are formed by mandrels moving in the radial direc- tion of the bullet. The groove-forming device can also be a tool of a phase compres- sion apparatus making a motion in the direction of the longitudinal axis of the bul- let. Figure 7 also schematically illustrates such a tool. The forming of longitudinal grooves is also possible by machining, such as milling.

[0064] Those skilled in the art will find it obvious that, as technology advances, the basic idea of the invention may be implemented in many different ways. The invention and its embodiments are thus not restricted to the examples described above but may vary within the scope of the claims.

Claims

Claims1. A bullet, a body part (2) of which bullet (1) consists of one material more resistant to deformation than lead, which bullet (1) includes a tapered front section (4) and a cylindrical section (3) defining the outer diameter of the bullet, which cylindrical section (3) includes on its outer surface grooves (8) substantially parallel with a longitudinal axis (A) of the bullet (1) to reduce friction between the outer surface of the bullet (1) and riflings of a barrel of a weapon and to enable the riflings of the weapon barrel to displace material from the outer diameter of the bullet (1) to the grooves (8).

2. A bullet according to claim 1, wherein a length (L4) of at least some of the grooves (8) on the cylindrical section (3) is at least 10%, preferably at least 30% and particularly preferably at least 40% of a length (L2) of the cylindrical sec- tion (3).

3. A bullet according to claim 1 or 2, wherein the length (L4) of at least some of the grooves (8) on the cylindrical section (3) is less than 80% of the length (L2) of the cylindrical section (3).

4. A bullet according to any one of the preceding claims, wherein the grooves (8) start on the cylindrical section (3) so far away from a bottom (7) of the bullet (1) that the groove (8) does not extend to the whole length of the neck of a case (9).

5. A bullet according to any one of the preceding claims, wherein at least some of the grooves (8) extend in the area of the tapered front section (4).

6. A bullet according to any one of the preceding claims, wherein the sum of widths of the grooves (8) is 10-50% of the length of the perimeter of the outer diameter of the cylindrical section (3).

7. A bullet according to any one of the preceding claims, wherein the depth of at least some of the grooves (8) is at least the height of a rifling of the barrel of the weapon.

8. A bullet according to any one of the preceding claims, wherein the number of the grooves (8) is at least six.

9. A bullet according to any one of the preceding claims, wherein the tapered front section (4) includes an endpiece (5) formed separated from the body part (2).

10. A bullet according to claim 9, wherein the endpiece (5) is fitted par- tially in a cavity (11) located in the front part of the bullet such that the cavity in- cludes an empty space (Ila) in the middle of the bullet behind the endpiece (5).

11. A cartridge, which includes a case (9) and a bullet (1) according to any one of claims 1-10.

12. A method for manufacturing a bullet, in which method, forming a bullet blank of a wire or bar of material that is more resistant to deformation than lead by cutting, forming a bullet from the bullet blank, forming grooves on the outer surface of a cylindrical section defining the outer diameter of the bullet substan- tially parallel with the longitudinal axis of the bullet, and calibrating the diameter of the bullet.

13. A method according to claim 12, in which, forming the longitudinal grooves in the bullet by a phase compression machine making a motion in the di- rection of the longitudinal axis of the bullet.

14. An apparatus for manufacturing a bullet, which apparatus includes a cutting device (21) for forming a bullet blank from a wire or bar by cutting, de- vices (22, 23) for working the bullet, a grooving device (25) for forming grooves (8) on the outer surface of a cylindrical section (5) defining the outer diameter of the bullet (1) substantially parallel with the longitudinal axis (A) of the bullet (1), and a calibration device (26).

15. An apparatus according to claim 14, wherein the grooving device (25) includes a front part (28) and a rear part (27), in which front part (28) has been formed protrusions (29) on the inner surface of its body, the height of which protrusions is dimensioned such that they extend in the radial direction of the bul- let (1) closer to the centre axis of the bullet (1) than what is the distance of the outer surface of the bullet (1) from the centre axis on the cylindrical section (5) of the bullet (1), and the rear part (27) of the grooving device (25) is configured to move in relation to the front part (28) in the longitudinal direction of the bullet (1).

16. An apparatus according to claim 14 or 15, wherein the device (22, 23) for working the bullet comprises means for forming a cavity (11) to the front end of the body part of the bullet blank (10) and the apparatus for manufacturing the bullet comprises means for setting an endpiece (5) in connection with the cav- ity (11).

Images