Exploding shotgun cartridge slug for military use

Abstract

A body 31 (see figure 2) for an explosive slug 3 for a shotgun cartridge 1 comprises a nose 32 (see figure 4) and a cavity 34 (see figure 4) that is open at a tip of the nose. The cavity is configured to receive an explosive charge 50. The nose may have a tapered or rounded profile. The body may be made of tungsten, copper alloy or lead.

Description

The present application relates to an explosive slug for a shotgun cartridge for military use. The present application also relates to a slug body of the explosive slug; a shotgun cartridge comprising the explosive slug; and processes for manufacturing the slug body, the explosive slug and the shotgun cartridge. Background Shotguns are usedin military applications as anti-personnel weapons at close range, or when loaded with slugs they are used forblowing hinges off doors orcausing damage to vehicles or opposing forces equipment. Existing military and law enforcement shotgun slugs have a destructive capability limited to the kinetic energy of the slug when it strikes its target. There is a need to increase the destructive capability of shotgun slugs to improve their performance in defeating hard targets such as lightly armored vehicles. Summary In a first aspect of the invention, there is provided a body for an explosive slug for use in a shotgun cartridge, the body comprising a nose and a cavity that is open at a tip of the nose, the cavity being configured to receive an explosive charge. The cavity may extend in a longitudinal direction of the body toward a heel of the body. The cavity may extend fromthetip and over about 50% to about 90% of the distance to the heel of the body. The cavity may extend fromthe tip and over about 75% to about 85% of the distance to the heel of the body. The nose may have a tapered or rounded profile. The body may comprise rifling on a bearing surface of the body. A channel may extend around the nose of the body. The rifling may extendto the channel. The body may comprise a second cavity that is open at the heel of the body and wherein the second cavity is separated from the cavity configured to receive an explosive charge by an internal wall. The body may be made of tungsten. The body may be made of one of copper alloy or lead. In a second aspect of the invention, there is provided an explosive slug comprising the bodyof the first aspect and an explosive charge receivedin the cavity ofthe body. The explosive charge maybe provided in a cartridge that is press fit into the cavity. The cartridge may comprise a primer disposed at or adjacent the tip ofthe body. The cartridge may be a rifle cartridge. The cartridge may be a . 22 LR rimfire cartridge. The slug may be configured for use with a shotgun comprising a 12 gauge bore. In a third aspect of the invention, there is provided a shotgun cartridge comprising the slug ofthe second aspect. The shotgun cartridge may further comprise propellant and wadding within a casing of the cartridge; wherein the wadding is provided in between the propellant and the slug. In a fourth aspect ofthe invention, there is provided a methodof manufacturing the bodyof the first aspect, the method comprising machining a solid metalworkpiece. In a fifth aspect of the invention, there is provided a method of manufacturing the slug ofthe second aspect, the method comprising machining a solid metal workpiece to form the slugbodyofthe first aspect; and push fitting an explosive charge into the cavity ofthe slug body. Machining of either the fourth or fifth aspect may comprise CNC machining. In a sixth aspect of the invention, there is provided a method of manufacturing the shotgun cartridge of the third aspect, the method comprising integrating the slug of second aspect into a casing of the shotgun cartridge. Brief Description of the Drawings Fig.i is a cross section of a shotgun cartridge 1 in accordance with an example of the invention; Fig. 2 illustrates a slug body configuredto receive an explosive charge in accordance with an example of the invention; Fig. 3 is an endviewofthe slug body of Fig. 2; Fig. 4 is a cross section of the slug body of Fig. 2; and Fig. 5 illustrates an explosive slug comprisingthe slug body of Fig. 2, according to a first example; Fig. 6 illustrates an explosive slug comprising the slug body of Fig. 2, according to a second example; Fig. 7 illustrates an explosive slug comprising the slug bodyofFig. 2, accordingtoa third example; and Fig. 8 illustrates an explosive slug comprisingthe slug bodyofFig. 2, according to a fourth example. Detailed Description With reference to Fig. 1, the cartridge 1 comprises a casing 2 which houses an explosive slug 3, wadding 4 and a propellant 5. As will be explained further below, the explosive slug 3 comprises an explosive charge 50 configuredto detonate when the explosive slug 3 impacts a target. For brevity, ‘the explosive slug 3’ is alternatively referredto as ‘the slug 3’ throughout. It will also be appreciated that the terms ‘explosive slug 3’, ‘exploding slug 3’ or ‘exploding shotgun cartridge slug 3’ may be used interchangeably. Any of these terms are used to refer to the slug 3 described herein, which is configured to explode on impact with a target. The casing 2 has a cylindrical wall 6 forming a tube that is closed at one end by a cap 7 containing a primer 8 and at the other by the slug 3. The wadding divides 4 an interior of the casing 2 in two, separating the propellant 5 fromthe slug 3 - the propellant 5 is provided adjacent the cap 7, while the slug 3 is providedthe other side of the wadding 4. In use, the shotgun cartridge 1 is used in the same way as a conventional shotgun cartridge. The primer 8 is set into the cap 7 and is configuredto ignite the propellent 5 when contacted by a firing pin to displace the wadding 4 and discharge the slug 3 down a barrel of a shot gun. The wadding 4 seals the gasses generated by ignition of the propellants and ensures that energyin the gas is not wasted by leakagebetweenthe slug 3 and the cylindrical wall 6 of the casing 2 and, thereafter, between the slugs and the barrel of the shotgun. In the example of Fig. 1, the wadding 4 comprises a disc shaped plug 4’ with a diameter substantially equal to or slightly less than the diameter of the cylindrical wall 6 of the casing 2 so that the wadding tightly fits therein. A nitro card 20 is providedbetween the wadding 4 and the propellant 5. The nitro card is a thin treated disc of fire-resistant cardthat acts to prevent burning propellant 5 igniting the wadding 4. The wadding 4 may be made from any suitable material such as plastic, cork ora biodegradable fibre such as paper. To manufacture the cartridge 1 of Fig. 1, a slug 3 as described herein is integrated into the casing 2 along with the other components in the usual way. The skilled person will be familiar with the manufacturing pro cess of shotgun cartridges comprising slugs and the use of an exploding slug 3 does not change the methods used in their manufacture. Fig. 2 illustrates a slug body 31 of the slug 3 in accordance with an example of the invention. For brevity, the ‘slug body3i’ is alternatively referred to as ‘the body3i’ throughout. Thebodysi comprises a tip T at one end of its longitudinal axis X-X and a heel H at the other. The tip refers to the end of the body 31 that is pointedtowardthe target in use. The outer surface of the body 31 comprises a nose 32 and a bearing surface 33. The bearing surface 33 is a straight sided cylindrical surface that, in accordance with firearms terminology, is the surface that contacts the bore of the barrel of the gun that the slug 3 passes through when fired. The nose 32 is a tapered or rounded surface that extends betweenthe bearing surface 33 and the tip T. The nose 32 is thereby configured to improve the flight characteristics of the slug 3 by cleanly parting the air when fired. As shown by Fig. 3 and Fig. 4, the body 31 comprises a cavity 34 that extends from the tip T and along the axis X-X. In the example illustrated by Fig. 4, the cavity 34 is one two cavities, the other - a ‘second cavity 35’ - extends fromthe heel H. The cavity 34 extending from the tip T is herein referred to as the ‘first cavity 34’. The first and second cavities 34,35 are concentric and centred onthe axis X-X. The diameter of the second cavity 35 is greater than the diameter of the first cavity 34. The first and second cavities 34,35 are separatedby an internal wall 36 of the body 31. In the illustrated example, the internal wall 36 comprises an annular wall 37 that extends into the second cavity 35 and circumferentially surrounds the first cavity 34; and an end wall 38 that caps the annular wall 37, serving as a base of the first cavity 34. The depth and diameter of the second cavity 35 can be selected to control the weight of the slug and thereby influence its ballistic characteristics. The first cavity 34 is open at the tip T so that the explosive charge 50 can be inserted into the first cavity 34 before it is assembled within thecasing 2 ofthe shotgun cartridge 1. The explosive charge 50 is configuredto detonate when the slug 3 impacts a target, giving the slug increased destructive capability. Any suitable explosive charge 50 may be used as long as the charge is configuredto detonate only when the slug 3 hits its target and not during handling or firing ofthe slug 3. To be large enough to receive sufficient explosive charge, the first cavity 34 preferably extends fromthe tip T and over about 50% to about 90% of the distance to the heel H of the body 31. More preferably, the first cavity 34 extends fromthe tip T and over about 75% to about 85% of the distance to the heel H ofthe body 31. The body 31 further comprises a channel 39 that extends circumferentially aroundthe nose32. The channel 39provides a weakening that encourages fragmentation ofthe bodysi when the explosive charge 50 detonates. Fragmentation increases the so-called ‘splash damage’ ofthe slug 3, particularly against soft, unarmouredtargets such as enemy personnel. As shown in Fig. 2 the body 31 further comprises rifling 40 onthe bearing surface 33. The rifling 40 comprises a series of ridges 41 that are spaced circumferentially about the bearing surface 33 (onlyone ridge4iis labelled in Fig. 2 for brevity). Each ridge 41 extends along a helical path fromthe heel H up to the channel 39. The rifling 40 is configuredto cause the slug 3 to spin about its axis X-X as it travels down the barrel of a gun when fired. As will be readily appreciated by the skilled person, the spinning of the slug 3 about its axis X-X increases its stability in flight and, therefore, the accuracy and range of the slug 3. Thebody 31 is manufactured by machining a solid metal workpiece. Therefore, the body 31 is simply constructed as a single component. The body 31 may be machined in any suitable way such as on a lathe orbyCNC machining. Thebody 31 may be made of tungsten. Tungsten is knownto resist break up on impact with a target. Therefore, by using tungsten forthe slug body3i, the slug’s 3 kineticenergy is focused into a smaller area, increasing penetration. Alternatively, the body 31 may be made of copper alloy or lead. By comparisonto tungsten, copper alloy and lead tend to break up more on impact with a target. Therefore, byusingcopper alloy or lead forthe slug body 31, the slug 3 shatters on impact with the target causing more fragmentation which may be propelledby the explosive force of a charge receivedin the first cavity 34. Fig. 5 illustrates an example slug 3 comprising an explosive charge 50 provided in a cylindrical cartridge 51. To manufacture the slug 3 of Fig. 5, the cylindrical cartridge 51 is push fit into the first cavity 34 of the body 31. By push fit it is meant that the cartridge 51 is an interference fit within the annular wall 37 of the first cavity 34 so as not to be dislodged during handling and firing of the slug 3. Therefore, it is desirable that the diameter of the cartridge 51 slightly exceeds the diameter of the annular wall 37. The cartridge 51 orthe first cavity 34 may be tapered to allowthe cartridge 51 to be easily locatedin the opening of the first cavity 34beforebeingpush fit home. The cartridge 51 comprises a cylindrical wall 52 that encloses a chamber 53 for receiving the explosive charge 50. The cylindrical wall 52 is capped at both ends by end walls 54,54’, enclosing the explosive charge 50 within the cartridge 51. A primer 55 is provided in the end wall 54 oriented towardthe tip T of thebody3i. In this way, the primer 55 is configuredto ignite the explosive charge 50 when the slug 3 hits a target. The explosive charge 50 may be in granular form. For example, the explosive charge may be a gun powder. Alternatively, the explosive charge may be a solid explosive material such as a plastic explosive. In the example illustrated by Fig. 6, the bodysi is of 12-gauge calibre and the first cavity 34 is provided with a cut down or blank firing .22 LR rimfire cartridge 70. The .22 cartridge is abundant, being reportedlythe most widelyused cartridge in the world today. Therefore, by providing a body 31 with a cavity 34 of the appropriate dimensions to receive said cartridges 70, an explosive slug 3 can be readily manufactured for use with standard 12-gauge shotguns. Rimfire cartridges 70 comprise a cylindrical casing 71 housing a granular explosive charge 50 (powder 50) that is enclosed at one end by the rim 72 and at the other by a bullet 73 or wadding (if a blank). The rim 72 comprises a primer 74 that ignites the explosive charge 50 when struck. To manufacture a slug 3 of the present example, a .22 cartridge 70 is press fit into a body 31 having an appropriately sized first cavity 34. The cartridge 70 is oriented so that the rim 72 is adjacent the tip T of the body 31. Therefore, the primer 74 within the .22 cartridge 70 acts to detonate the powder 50 when the slug 3 impacts its target. Preferably a blank cartridge 70 is used, but a cartridge 70 containing a bullet 73 can also be used if the bullet 73 is sawn down before the cartridge 70 is inserted into the cavity 34 (as illustrated). It will be appreciated that other calibre cartridges couldbe used by appropriately sizing the cavity 34. It will be further appreciated that in other, unillustrated examples, a cartridge other than a rimfire cartridge 70 may be used such as a centrefire cartridge. Fig. 7 illustrates an example slug 3 comprising an explosive charge 50 provided as a solid explosive material 60. To manufacture the slug 3 of Fig. 7, the solid explosive material is push fit directly into the first cavity 34. Therefore, the explosive charge 50 is in direct contact with the bodysi instead of being providedin a cartridge as in the above examples. The solid explosive charge 60 may be a plastic explosive that is configuredto detonate on impact with the target. Alternatively, though not shown, a primer may be inserted into the explosive charge 50 to be adjacent the tip T of the body 31. Usinga primer allows a more stable plastic explosivetobeusedthatis less likelyto be detonated by accident. The example illustrated by Fig. 8 is the same as the example illustrated by Fig. 7 except for a conical cut out 61 in the solid explosive material 60 that opens adjacent the tip T of the body 31. The conical cut out 61 is centred on the axis X-X and creates a shaped charge that increases the penetrative effect of the solid explosive charge 60 when the slug 3 hits a target. The science of shaped charges is known to the skilled person and will not be elaborated on here. The applicant has foundthatthe destructive capability of the slug 3 comprising an explosive charge 50 as describedin any of the above examples is markedly increased and is particularly useful in military applications. The slug 3 provides an exploding force on impact that is pushedinto its target for more effective penetration. Indeed, it is expected that the use of an explosive charge 50 will enable the slug 3 to defeat armour that would resist regular small arms fire. It is further expected that the slug 3 will have a range of up to 65 yards, making it effective against low flying drones and helicopters. The slug 3 therefore has application where a penetrating or exploding projectile causing shrapnel is required. Anon-exhaustive list of such military 5 applications includes: • Damage to vehicles including engine blocks and other critical parts causing an engine to fail. 10   • Causing destructive damage to wheel rims and tyres, causing vehicles to become disabled. •      Causing destructive damage to reinforced doors, windows, and other structures, including penetrating brick or block walls. 15 • Causing damage to RIB boats or other small vessels.

Claims

1. A body for an explosive slug for use in a shotgun cartridge, the body comprisinga nose and a cavity that is open at a tip of the nose, the cavity being configured to receive an explosive charge.

2. Whereinthe cavity extends in a longitudinal direction of the bodytowarda heelof the body.

3. A body according to claim 2, wherein the cavity extends from the tip and overabout 50% to about 90% of the distance to the heel of the body.

4. A body according to claim 3, wherein the cavity extends fromthe tip and overabout 75% to about 85% of the distance to the heel of the body.

5. A body according to any preceding claim, whereinthe nose has ataperedorrounded profile.

6. A body according to any preceding claim, whereinthe body comprises rifling ona bearing surface of the body.

7. A body according to any preceding claim, wherein a channel extends around thenose of the body.

8. A body according to claim 7 when dependent on claim 6, wherein the riflingextends to the channel.

9. A body according to any of claims 2 to 8, wherein the body comprises a secondcavity that is open at the heel of the body and whereinthe second cavity is separated fromthe cavity configured to receive an explosive charge by an internal wall.

10. A body according to any preceding claim, whereinthe bodyis made oftungsten.

11. A body according to any of claims 1 to 9, wherein the bodyis made of one ofcopper alloy or lead.

12. An explosive slug comprising the body of any of claims 1 to 11 and an explosivecharge receivedin the cavity of the body.

13. The slug of claim 12, wherein the explosive charge is providedin a cartridge thatis press fit into the cavity.

14. The slug of claim 13, whereinthe cartridge comprises a primer disposed at oradjacent the tip of the body.

15. The slug of claim 13 or claim 14, whereinthe cartridge is a rifle cartridge.

16. The slug of claim 15, whereinthe cartridge is a .22 LR rimfire cartridge.

17. The slug of any of claims 12 to 16, whereinthe slug is configuredfor use with ashotgun comprising a 12 gauge bore.

18. A shotgun cartridge comprising the slug of any of claims 12 to 17.

19. A shotgun cartridge according to claim 18, wherein the shotgun cartridge further comprises propellant and wadding within a casing of the cartridge; wherein the wadding is providedin between the propellant and the slug.

20. Amethodofmanufacturingthebodyofany of claims ito 11, the method comprising machining a solid metal workpiece.

21. A method of manufacturing the slug of any of claims 12 to 17, the methodcomprising machining a solid metal workpiece to form the slug body of any of claims 1 to 11; and push fitting an explosive charge into the cavity of the slug body.

22. A method according to claim 20 orclaim 21, wherein machining comprises CNCmachining.

23. A method of manufacturing the shotgun cartridge of claim 18 or claim 19, the method comprising integrating the slug of any of claims 12 to 17 into a casing of the shotgun cartridge.

Images