Ammunition and explosives – Cartridges – Projectile structure
Patent
1986-08-21
1991-03-19
Tudor, Harold J.
Ammunition and explosives
Cartridges
Projectile structure
102222, 102448, 102473, 102476, 102491, 102532, F42B 500, F42B 710, F42B 1204, F42B 1210
Patent
active
050000942
DESCRIPTION:
BRIEF SUMMARY
The invention relates to shotgun cartridges having an explosive armour piercing shell which can be produced economically and which can be fired safely from a conventional shotgun.
Modern impact explosive shells have a "bore safe" arming mechanism, i.e. one which prevents the shell from being detonated in the gun barrel and which arms the shell, to prepare it to explode on impact, after it has travelled far enough to explode without damaging the gun or gunner. The distance at which the shell can be armed safely is dependant on the size of the shell (due to the magnitude of the explosion) and the amount of shrapnel and debris which is hurled rearwards towards the gunner on explosion. These mechanisms are generally complex and expensive and they occupy a significant volume in the shell thereby reducing the volume of the main explosive charge.
Were it not for the requirement for a "bore safe" arming mechanism and for arming to take place only after the shell has travelled a safe distance, the detonating device could be a simple primer in the nose of the shell which would detonate from the percussion caused on impact. In conventional shells simple impact primers cannot be used. Known arming mechanisms use a firing pin or hammer mechanism within the shell for mechanical detonation or, alternatively, a piezo-electric crystal to generate electricity on impact. Both of these types of systems can be inhibited or held inoperable by the arming mechanism and both allow the detonation to be located at the rear of the main explosive charge, necessary in particular for detonation of shaped explosive charges. Unfortunately, both systems add complexity and cost to the shell and a further disadvantage of the mechanical systems is that they are relatively slow acting. Although piezo-electric systems are faster they are not instantaneous not related to the speed of electricity. This is because the metallic element inside the detonator requires current for a significant time before it is hot enough to cause detonation.
If a shaped charged is used then a long projection, usually an empty cylinder or cone, is added to the front of the explosive charge of the shell so that detonation occurs before the charge has been able to travel the length of the projection. Were this not the case, then if the face of the charge impacted before detonation, the conical shape of the charge would be distorted and its armour penetration effect, known as the Monroe effect, would be lost.
Clearly, the fastest possible ignition times will be achieved with direct percussion of a primer which, once initiated, enables detonation to progress through a high explosive chain so rapidly that no projection stand off is needed. This would have the added advantage of being simple and cheap to produce. However, the problem is to control such a detonation device with a simple and reliable "bore safe" arming device.
According to a first aspect of the present invention a shotgun cartridge has an armour piercing shell which includes a main charge arranged to be detonated or exploded by direct percussion of a primer the cartridge including a bore safe arming device, characterized in that the arming device is arranged to interrupt the detonation process after detonation of the primer.
According to a second aspect of the present invention a shotgun cartridge has an armour piercing shell which includes a main charge arranged to be detonated or exploded by direct percussion of a primer, the cartridge including bore safe arming device, characterized in that the arming device is arranged to separate from the shell, to arm the shell, after firing of the shell from the barrel of a gun.
According to a third aspect of the present invention a shotgun cartridge has an armour piercing shell which includes an open base or rear portion to prevent shrapnel being thrown to the rear on detonation.
The arming mechanism may comprise a cylindrical element disposed within the main charge and arranged to be withdrawn from the main charge after firing of the shell from the cartridge.
Prefera
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