WO2014125510A1

WO2014125510A1 - Bullet for firearm and method for manufacturing the same

Info

Publication number: WO2014125510A1
Application number: PCT/IT2013/000047
Authority: WO
Inventors: Maurizio DELTRATTI
Original assignee: LEAD EXTRUSIONS S.r.l
Priority date: 2013-02-14
Filing date: 2013-02-14
Publication date: 2014-08-21

Abstract

One aspect of the invention relates to a method of making a bullet for a firearm, comprising the steps of: providing a wire in a material suitable for making the core of the bullet and a tube in a material suitable for making a casing of said core; truncating said wire so as to obtain a section of wire of suitable weight and dimensions for making the core of the bullet. truncating said tube so as to obtain a section of tube suitable for containing at least partially said section of wire; inserting the section of wire in the section of tube; pressing the assembly thus obtained into the cavity of a moulding die so as to make the section of tube integral with the section of wire, said cavity having the shape of the bullet to be moulded.

Description

"Bullet for firearm and method for manufacturing the same"

DESCRIPTION

[0001] The present invention relates to a bullet for a firearm, in particular for a gun or rifle.

[0002] As is known, in the sector of sports, defence or hunting firearms, a bullet is understood as a round or projectile having a tapered, pointed or flat end.

[0003] Currently bullets are produced basically using four methods .

[0004] A first production method involves making the bullets in a very hard lead-antimony or lead-tin-antimony alloy, furnished with one or more waxy lubricant rings which act as lubricant. These are the most economical rounds available on the market, are precise and are used for sports shooting.

[0005] However, such bullets have the defect of leaving deposits of lead inside the barrel, which are very difficult to remove, and of emitting significant amounts of smoke during firing on account of the combustion of the wax inside the barrel of the gun. Nor do they permit an overly pressed loading of the ammunition.

[0006] This smoke also contains considerable quantities of lead which passes to the vaporous state on account of its contact with the gunpowder and with the overheated barrel of the firearm and which thus proves toxic for the shooter and those around him.

[0007] These are generally made by melting the alloy in a preheated mould and then drawn and filled with lubricant wax.

[0008] A second production method leads to the production of an armoured bullet, consisting of a core in lead- antimony alloy covered by a sheet of brass or steel or copper closed at the tip or at the bottom or in the central part.

[0009] This type of round is widely used for defence firearms or for hunting with a rifle.

[0010] It is instead little used for sports shooting in that the bullets are more expensive than those in lead, rapidly wear the barrel of the gun on account of the hardness of the armour, are dangerous on account of the risk that the bullet, having an extremely hard tip, could rebound towards the shooter and in many firing ranges are not allowed since they ruin the system for collecting and stopping the rounds at the end of the firing line.

[0011] Ammunition of this type of bullet may be subjected to highly pressed loading.

[0012] These bullets are generally manufactured by moulding of a lead alloy core in a copper, brass or steel cup.

[0013] In a third production method the bullet is coated galvanically . This type of round consists of a core in lead alloy covered with a layer of copper or copper and other metals and alloys such as brass or nickel. These bullets do not suffer from the problems of lead rounds, and do not therefore emit smoke during firing and can even be used in indoor firing ranges, do not coat the inner part of the round in lead and can be loaded in the same way as armoured bullets.

[0014] The main drawback of this type of bullet is the cost of the coppering operation, which lasts over twelve hours for a covering of 120 micron (the standard coating for this type of bullet) .

[0015] A second drawback of this product is the imprecision of the thickness of the coating on account of the fact that this is made with a rotating drum in a solution of copper and thus takes place with a statistical distribution of such copper. The result is that at the end of the process some bullets have a greater thickness of copper than rounds present in the same bath.

[0016] The systems which carry out this type of coppering generally use cyanide baths. The process is delicate and if an electricity cut occurs during processing or if the base product is not properly degreased apparently cohesive layers of copper may form which in actual fact during the firing flake causing significant problems in terms of precision and safety for the shooter.

[0017] These bullets moreover are not suitable for producing rifle rounds in that the galvanic coating is not sufficiently resistant to the speed reached in the barrel of many types of firearm. The bullets are produced almost always by melting an undersized round in lead which is then coated in the galvanic bath described above .

[0018] A fourth production method involves coating the bullet in heat-resistant paint.

[0019] These bullets are economical and replace the wax with an epoxy or other type of heat resistant paint, but their performance in terms of splicing is no better than lead bullets.

[0020] The paint itself is moreover often subject to combustion with the consequent emission of potentially toxic vapours.

[0021] The purpose of the present invention is to propose a production method of a bullet able to overcome the drawbacks complained of in relation to the prior art.

[0022] Another purpose of the invention is to propose a bullet with superior ballistic characteristics than those of current bullets.

[0023] Such purposes are achieved by a production method of a bullet according to claim 1 and by a bullet according to claim 14. The dependent claims show preferred or advantageous embodiments of the method and of the bullet according to the invention.

[0024] The features and advantages of the invention will be clearer from the description given below of its preferred embodiments, made by way of non-limiting examples, with reference to the appended drawings , wherein:

[0025] - Figures la-lg show some steps of a production method of the bullet according to the invention;

[0026] - Figure 2 shows a bullet for a gun according to the invention, in one embodiment;

[0027] - Figure 3 shows a bullet for a gun in another embodiment;

[0028] - Figure 4 shows a bullet for a gun in a further embodiment;

[0029] - Figure 5 shows a bullet for a gun in a still further embodiment;

[0030] Figure 6 shows an example of a bullet for a rifle according to the invention;

[0031] Figures 7a-le show some steps of another production method of the bullet according to the invention, starting from a sheet of aluminium or aluminium alloy to make the casing of the bullet;

[0032] Figure 8 shows a bullet obtained using the method in the previous figures;

[0033] Figures 9a-9g show some steps of a variation of the production method of the bullet described in figures 7a- 7e; and

[0034] Figure 10 shows a bullet obtained using the method in the previous figures.

[0035] In said drawings, reference numeral 1; 100 globally denotes a bullet according to the invention for a gun and for a rifle respectively.

[0036] The bullet 1 for a gun has a tapered but rounded front end 1', and a rear end 1" wider than the front end. The bullet 100 for rifles is a longer and thinner shape than the bullet for guns, with a pointed front end 100'.

[0037] The bullet 1; 100 comprises in any case a core 10, preferably made from lead alloy, and a casing 20 which covers said core 10 at least partially. As will be described below, in a preferred embodiment shown in figures 1-6, said casing 20 is obtained from a section of tube, preferably in aluminium alloy. In an embodiment variant, shown in figures 7-10, said casing 20 is obtained from a sheet of aluminium or aluminium alloy.

[0038] In one embodiment shown in figures 2 and 6, the casing 20 leaves the front end 10' of the core 10 and at least a portion of the rear end 10" of said core, bare. In other words, the casing 20 may be defined a "tubular" casing.

[0039] In one embodiment shown in figures 3 and 8, the casing 20 covers the entire front end 10' of the core 10 but leaves at least a portion of the rear end 10" of said core bare.

[0040] In one embodiment shown in figures 4 and 10, the casing 20 leaves the front end 10' of the core 10 bare but completely covers the rear end 10" of said core, forming a "cup" casing.

[0041] In one embodiment shown in figure 5, the casing 20 covers the core 10 entirely.

[0042] According to one aspect of the invention the casing 20 is of variable thickness, and in particular increases in thickness towards its rear end. This way, the barycentre of the bullet is shifted forward improving firing accuracy and stabilising the rotation more efficiently. In fact, the aluminium is distributed to a greater extent on the rear part of the bullet so as to leave more lead towards the tip. It follows that, lead being denser than aluminium, for the same shape the barycentre shifts forward.

[0043] According to a first aspect of the invention shown in figures la-lf, the method of making the bullet commences by providing a wire 30 in a material suitable for forming the core 10 of the bullet, for example a wire in lead alloy, and a tube 40 in a material suitable for making the casing 20 of said core, preferably aluminium alloy.

[0044] For example, said wire and tube are made to advance parallel to each other along a single production line (figure la) .

[0045] The wire 30 is truncated so as to obtain a section of wire 30' of suitable weight and dimensions for making the core 10 of the bullet.

[0046] Similarly, the tube 40 is truncated so as to obtain a section of tube 40' suitable for containing at least partially said section of wire (figure lb) . For example, after truncation the section of tube is brought into the truncating position of the section of wire (figure lc) .

[0047] The section of wire 30' is then inserted in the section of tube 40', for example by means of a punch 50 (figure Id) . Both are then brought in front of a moulding die 60 (figure le) . Said moulding die 60 has a moulding cavity 62 of a corresponding shape to the shape of the bullet to be obtained.

[0048] For example, the punch 50 brings both pieces inside the moulding die with a pressure suitable for preventing the pieces to be moulded from moving.

[0049] The assembly composed of the section of wire 30' inserted in the section of tube 40' is pressed into the moulding cavity 62 so as to make the section of tube 40' integral with the section of wire 30* (figure If).

[0050] More precisely, the moulding cavity 62 being shaped so as make one end of the section of wire 30' tapered (which will become the front end) said pressing causes a radial deformation of one end of the section of tube 40 such as to make said end of the section of tube adherent to said tapered end of said section of wire. In other words, the moulding die 60 contemporarily forms both the core 10 and the casing 20, making them closely connected to teach other.

[0051] As explained above, depending on the type of bullet to be obtained, and therefore on the length of the section of tube 40', at the end of the pressing step the end of the portion of tube 40' may surround the tapered end of the section of wire 30', covering it completely or leaving the tip bare.

[0052] In other words, when the section of wire 30' is inserted in the section of tube 40', if the front end of the section of tube is made to project axially in relation to the front end of the section of wire, at the end of the pressing step said front end of the portion of tube surrounds said tapered end of the section of wire covering it completely.

[0053] According to one embodiment, the moulding die 60 comprises a front part 60 ' bearing the moulding cavity 62 and a rear part 60" suitable for forming the rear end 1", 100" of the bullet 1; 100. For example, it is the rear die 60" which presses the section of wire 30' and the section of tube 40' into the moulding cavity 62, so that both the front part and the rear part of the bullet are formed simultaneously.

[0054] According to one embodiment, when the section of wire 30' is inserted in the section of tube 40', the rear end 40" of the section of tube projects axially in relation to the rear end of the section of wire. In this case, the rear part 60" of the moulding die is suitable for causing a radial deformation of the rear end 40" of the section of tube so as to close the rear end 10" of the core at least partially with the section of tub 40'. Depending on how far the portion of tube projects rearwards to the portion of wire, a total or partial coverage of the rear end of the core is achieved.

[0055] The moulded bullet is then expelled from the die and continues its processing for any drawing or surface treatment steps (figure lg) .

[0056] If necessary, the aluminium tube may be left sufficiently long to permit a deep drawing process of the bottom so as to cover it completely, for example performed by a suitable rear die. [0057] According to one embodiment, the tube 40 and the wire 30 are chosen so that the outer diameter of the wire is substantially equal to the inner diameter of the tube.

[0058] In one variant of performing the method, for example before the truncating step, the tube 40 is subjected to a calibration of its inner diameter and/or outer diameter. Such calibration step makes it possible for example to obtain a section of tube of varying thickness along its axis, and in particular a tube of varying thickness which increases in thickness towards its rear end.

[0059] Moreover, before the truncation, the tube may be recalibrated as needed.

[0060] In one variant of performing the method, before the truncation, the wire 30 is subjected to a step of extrusion.

[0061] It is to be noted that the production method of the tube described above may be conducted in a similar manner even with a copper or brass tube or tube made from any other type of alloy.

[0062] According to another aspect of the invention, the casing 20 of the bullet is made from aluminium or aluminium alloy and is obtained from a sheet 70 according to the method described below.

[0063] The sheet 70 is moulded so as to form a cup 72 having the dimensions suitable for constituting the casing 20 of the bullet. For such moulding operation of the cup, a cup moulding die 80 and a punch 90 are used.

[0064] Since very hard aluminium alloys cannot be moulded using the traditional method for making armoured rounds, inasmuch as such alloys if subjected to excessive deformations tend to create micro fractures which lead to breaking of the cup during processing, the method of making the bullet from an aluminium sheet requires several particular expedients.

[0065] One of these involves deforming the sheet 70 by using a die 80 and a punch 90 kept in rotation at a suitable number of revs during pressing and using a suitable solid lubricant, such as boron nitride.

[0066] Keeping the die 80 and the punch 90 in rotation, the lubricant is evenly distributed on the surface of the piece during the deformation and prevents the formation of cracks in the aluminium cup 72 which will be moulded definitively once the lead core has been inserted.

[0067] Figures 7a-7c show the moulding of the aluminium sheet by means of a die 80 and punch 90 to obtain the cup casing 72. In this case, the bottom of the cavity 82 of the die 80 is shaped in a corresponding manner to the tip 1 of the bullet 1.

[0068] Contemporarily, a section 75 of lead wire is truncated and moulded to form the core to insert in the cup casing 72.

[0069] The section 75 of lead wire and the aluminium cup 72 are inserted in a moulding die 80 to make the desired profile of the bullet. For example, the moulding die of the bullet 80 is the same die which has moulded the cup casing 72. Consequently, the section 75 in lead is inserted in the cavity 82 of the die which has already performed the moulding of the cup casing (figure 7d) .

[0070] A press 92 proceeds with the moulding of the bullet inside the die (figure 7e) .

[0071] In particular, a moulding die is made to advance as far as the moulding position and the partial rear closing of the aluminium cup is performed, so as to obtain the bullet in figure 8.

[0072] In the embodiment variation shown in figures 9-10, the production method is the same as that described above, but the section of lead wire 75 and the aluminium cup 72 are inserted in the moulding die placing the open part of the cup 72 at the front. In other words, the bottom of the cavity 82 of the moulding die 80 is shaped in a corresponding manner to the bottom of the bullet.

[0073] This way a bullet 1 is obtained with a breakable tip 1' and bottom 1" covered by the aluminium (figure 10).

[0074] The bullet produced starting from a sheet of aluminium or aluminium alloy has casing characteristics analogous to those currently armoured in brass, but the hardness of the casing may be greatly modulated by varying the alloy as needed.

[0075] The aluminium alloy in addition lends itself to being anodised in numerous colour variants and levels of hardness. Lubricants such as disulphur molybdenum or boron nitride can even be inserted inside the aluminium oxide of the anodised layer.

[0076] This production method also applies to rifle bullets modifying the shape of the die and the weight of the lead section as needed.

[0077] The aluminium casing obtained from the sheet is used in particular in those cases in which a hermetic closing of the bottom of the bullet or tip is needed.

[0078] The production methods described and the resulting bullets have numerous advantages compared to the prior art .

[0079] The production process involves the cold processing of all the components in each step of the process. This way problems of emission of lead vapours are avoided and energy consumption significantly reduced compared to the lead rounds generally obtained by fusion.

[0080] During the loading of the bullet the user does not come into contact with the bare lead rounds but only touches the casing in aluminium alloy. [0081] The use of aluminium in place of brass and of copper in the armoured rounds reduces production costs, aluminium being much cheaper than copper and brass, while maintaining ballistic performance however.

[0082] The use of the tube in place of the sheet, both of aluminium and of brass or copper , further reduces the cost of the raw materials used reducing production waste.

[0083] The use of the tube in place of the sheet also reduces processing costs in that the bullet can be made on a single production line making the separate preparation of a lead core on the one hand and a brass cup on the other and their moulding in a third machine unnecessary.

[0084] Once anodised, the aluminium can achieve extremely high levels of surface hardness should a sliding of the barrel at high speeds be needed, while maintaining the material under the anodised layer much more malleable than copper and brass. This makes it possible for the rifling of the barrel to engage the surface of the bullet to a greater extent thereby improving firing accuracy.

[0085] Aluminium and its alloys have a considerably different density to that of lead and its alloys, but also to that of copper. By suitably modifying the thickness of aluminium, which normally engages the rear part of the bullet to a greater extent, the barycentre of the bullet can be shifted forward improving firing accuracy and stabilising the rotation more efficiently.

[0086] The use of the tube in place of the galvanic coating makes it possible to significantly increase the precision of the thickness of the casing.

[0087] The use of aluminium in place of galvanic copper considerably reduces production costs.

[0088] The elimination of the galvanising procedure makes it possible to avoid producing all the pollutant waste innate to the galvanising procedure itself among which the baths containing cyanide and considerably reduces the quantity of electricity used.

[0089] The bullet covered by the aluminium tube permits loading similar to that of traditional armoured bullets.

[0090] The tip of bare lead keeps the bullet breakable permitting its use where armoured rounds are prohibited.

[0091] A person skilled in the art may make modifications and adaptations to the implementations of the production methods of the bullet according to the invention and to the bullets deriving from the same, replacing elements with others functionally equivalent so as to satisfy contingent requirements while remaining within the sphere of the following claims. Moreover, each of the characteristics described as belonging to a possible embodiment may be realised independently of the other embodiments described.

Claims

1. Method of making a bullet for a firearm, comprising the steps of:

- providing a wire in a material suitable for making the core of the bullet and a tube in a material suitable for making a casing of said core;

- truncating said wire so as to obtain a section of wire of suitable weight and dimensions for making the core of the bullet;

- truncating said tube so as to obtain a section of tube suitable for containing at least partially said section of wire;

- inserting the section of wire in the section of tube;

- pressing the assembly thus obtained into the cavity of a moulding die so as to make the section of tube integral with the section of wire, said cavity having the shape of the bullet to be moulded.

2. Method according to the previous claim, wherein said cavity is shaped so as make one end of the section of wire tapered, and wherein said pressing causes a radial deformation of one end of the section of tube such as to make said end of the section of tube adherent to said tapered end of said section of wire.

3. Method according to the previous claim, wherein at the end of the pressing step said front end of the portion of tube surrounds said tapered end of the section of wire without covering it completely.

4. Method according to claim 2, wherein when the section of wire is inserted in the section of tube, the front end of the section of tube projects axially in relation to the front end of the section of wire in such a way that at the end of the pressing step said front end of the portion of tube surrounds said tapered end of the section of wire covering it completely.

5. Method according to any of the previous claims, wherein the moulding die comprises a front part bearing said cavity and a rear part suitable for forming the rear end of the bullet.

6. Method according to any of the previous claims, wherein, when the section of wire is inserted in the section of tube, the rear end of the section of tube projects axially in relation to the rear end of the section of wire.

7. Method according to claims 5 and 6, wherein the rear part of the moulding die is suitable for causing a radial deformation of the rear end of the section of tube so as to close the rear end of the core at least partially with the section of tube.

8. Method according to any of the previous claims, wherein the tube and the wire are chosen so that the outer diameter of the wire is substantially equal to the inner diameter of the tube.

9. Method according to any of the claims 1-7, wherein, before the truncating step, the tube is subjected to a calibration of its inner diameter and/or outer diameter.

10. Method according to the previous claim, wherein said calibration makes it possible to obtain a section of tube of varying thickness, in particular increasing towards its rear end.

11. Method according to any of the previous claims, wherein, before the truncation, the wire is subjected to a step of extrusion.

12. Method according to any of the previous claims, wherein the wire is made in lead alloy.

13. Method according to any of the previous claims, wherein the wire is made in an aluminium alloy.

14. Bullet for firearm, comprising a core and a casing of said core made from a section of tube.

15. Bullet according to the previous claim, wherein said casing is such as to leave at least a portion of the rear end of the core, bare.

16. Bullet according to claim 14 or 15, wherein said casing is tubular.

17. Bullet according to claim 14, wherein said casing completely closes the rear end of the core.

18. Bullet according to any of the previous claims, wherein the casing has a variable thickness.

19. Bullet according to the previous claim, wherein the casing increases in thickness towards its rear end.

20. Bullet according to any of the claims 14-19, wherein said casing is made from aluminium alloy.

21. Method of making a bullet for a firearm, comprising the steps of:

- providing an aluminium sheet or aluminium alloy and a wire in a material suitable for making the core of the bullet;

- truncating said wire so as to obtain a section of wire of suitable weight and dimensions for making the core of the bullet.

- moulding said sheet so as to form a cup suitable for constituting the casing of the bullet;

- inserting the section of wire and the cup in a cavity of a moulding die;

- pressing the section of wire and the cup so as to obtain the bullet.

22. Method according to the previous claim, wherein the bottom of the cavity of the moulding die is shaped in a corresponding manner to the tip of the bullet, and wherein the open end of the cup is deformed so as to partially close the bottom of the core o the bullet.

23. Method according to claim 21, wherein the bottom of the cavity of the moulding die is shaped in a corresponding manner to the rear end of the bullet, and wherein the open end of the cup is deformed so as to partially close the tip of the bullet.

24. Method according to any of the claims 21-23, wherein the moulding of the sheet takes place by means of a die and a punch which are kept in rotation during the pressing, so as to evenly distribute a solid lubricant on the surface of the sheet during the deformation.

25. Bullet for a firearm, comprising a core and a casing of said core, characterised in that said casing is obtained from a sheet of aluminium or aluminium alloy.

26. Bullet according to the previous claim, wherein said casing has a cup shape which hermetically seals the rear end or tip of the core.