Relating to ammunition

Abstract

This invention relates to a improvements relating to munitions, specifically to coating small arms ammunition with decoppering agents, as a replacement in lead free ammunition. There is a method of manufacturing a coated metallic projectile for a rifled barrel, comprising; providing a metallic projectile cup with a coating of a decoppering agent located thereon, to provide a coated metallic projectile cup; causing the coated metallic projectile cup to be drawn through a plurality of dies to form a drawn coated metallic projectile.

Claims

1. A method of manufacturing a decoppering agent coated metallic projectile for a rifled barrel, the method comprising: coating a metallic projectile cup with a decoppering agent, to provide a coated metallic projectile cup; and causing the coated metallic projectile cup to be drawn through a first die, then drawn through at least a second die and then drawn over an inner core to form a drawn coated metallic projectile that comprises an outer jacket disposed over the inner core, the outer jacket derived from the coated metallic projectile cup and comprising the decoppering agent.

2. The method according to claim 1, wherein the thickness of the coating of the decoppering agent on the metallic projectile cup is in the range of from 0.10 microns to 100 microns.

3. The method according claim 2, wherein the thickness of the coating of the decoppering agent on the metallic projectile cup is in the range of from 5 microns to 15 microns.

4. The method according to claim 1, wherein the decoppering agent is tin.

5. The method according to claim 1, wherein the metallic projectile cup is gilding metal, copper or copper alloys thereof.

6. The method according to claim 1, wherein prior to coating the metallic projectile cup with the decoppering agent, the method further includes: providing a precursor stock material with a coating of the decoppering agent located thereon, to provide a coated precursor stock material; and causing the coated precursor stock material to be formed into the coated metallic projectile cup, by one or more of rolling, drawing, extrusion, stamping.

7. The method according to claim 6, wherein the decoppering agent is applied to the precursor stock material or metallic projectile cup by one or more of electrolysis, electroless deposition, vapour deposition, chemical vapour deposition, co-depositing/alloying.

8. The method of claim 1, further comprising forming a coated metallic cartridge case for the coated metallic projectile, by: coating a metallic cartridge cup with a decoppering agent, to provide a coated metallic cartridge cup; and causing the coated metallic cartridge cup to be drawn through a plurality of dies to form the drawn coated metallic cartridge case.

Description

(1) An arrangement of the invention will now be described by way of example and with reference to the accompanying drawings of which;

(2) FIG. 1 shows a round with a layer of decoppering agent.

(3) FIG. 2 shows a method of making the coated metallic projectile cup.

(4) FIG. 3 shows a round located in a rifled barrel.

(5) FIG. 4 shows a complete round with the projectile of the invention.

(6) As shown in FIG. 1, a small arms round 1 comprising an inner core 5, outer jacket 3, an ogival portion 2, and a rearwardly located boat tailed portion 8.

(7) The inner core 5, has a drawn outer jacket 3, the drawn outer jacket 3 comprises a layer of drawn decoppering agent 4, such as tin, on the exterior surface. The total outer diameter 7 defines the calibre, which is the sum of the drawn decoppering agent, drawn outer jacket and inner core.

(8) During the drawing process, a gap 6 is often left between the inner core 5 and the drawn outer jacket 3, the gap 6 may comprise a particulate filler, air gap or ceramics.

(9) As shown in FIG. 2, there is provided a precursor stock material 10, such as a sheet of copper 13, with a deposed layer of decoppering agent 14 deposed thereon. Tin plating is a well known process, and the tin may be applied by any known method.

(10) The precursor material 10 may be deformed, punched, pressed to provide a decoppering agent coated metallic projectile cup 20. The cup having a wall 23, with an outer layer of decoppering agent 24, deposed thereon. The cup may then be used directly in a draw process to provide elongated cup 21, which is ready to receive an inner core in opening 22. The walls 23 of the elongate cup, comprise the decoppering agent located on the outer surface of the walls 23.

(11) Alternatively, the decoppering agent deposition may be applied to both surfaces of the precursor stock material. In an alternative arrangement the precursor stock material 10a, comprises a sheet of copper 13, with a deposed layer of decoppering agent 14a. 14b deposed on both sides. The subsequent processing into a metallic projectile cup 20a provides a metallic projectile cup which is enveloped with decoppering agent.

(12) In an alternative arrangement, a ready formed metallic projectile cup 19, may be coated directly with a decoppering agent, either on just the outer surface to provide cup 20 or both the inner and outer surface to provide cup 20a.

(13) As shown in FIG. 3, in use the round of ammunition comprising the assembled primed and filled cartridge case 33, together with a projectile 31 are fired from a gun having a rifled barrel 34, in the conventional manner, i.e. by chambering the round within the gun chamber 35, and arranging for the primer cap (not shown) to be struck by a firing pin.

(14) When the projectile passes from the gun chamber into the rifled part of the barrel, by virtue of its greater diameter, the inner core 39 becomes engraved by the rifling 37. The diameter of the monolithic body 39 and associated jacket 32 should preferably be substantially equal to or less than the diameter of the rifling grooves 36, 38.

(15) The jacket 32 is of a malleable material which can be copper or a copper alloy and comprises a decoppering agent coated thereon. This jacket 32 is of a thickness greater than the depth of the rifling grooves, and is of a relatively softer material than that of the monolithic body 39, it can also engrave more readily, and thus contribute for this reason also to a reduction in the engraving force required. Because the jacket 32 is thicker than the depth of rifling, engraving can take place entirely within the coating so that the hard metal of the monolithic body 39 is kept substantially out of contact with the material forming the rifling of the gun barrel. Therefore, despite the hardness of the material forming the main part of the monolithic body 39, barrel wear from this factor is minimised.

(16) Turning to FIG. 4, a round 41 is shown. The cartridge assembly 41 comprises a casing 42 and a decoppering agent coated projectile 44. The casing 42 has a hollow section 46, which will contain propellant for displacement of the projectile 44. The casing 42 further comprises a head 48 at the end opposite to the projectile 44 which comprises a chamber 40 for a percussion cap (not shown), and a flash tube 42 for communication of an ignition charge from the percussion cap to the inside of the casing 42 and thus the propellant. The walls of the chamber 46 are formed integrally with the head 48. The walls 46 of the cartridge case chamber may also be plated with a decoppering agent, on the inner surface, outer surface or both. Such a cartridge casing may typically be formed of brass, steel or titanium.