Ammunition and explosives – Cartridges – Practice projectile type
Reexamination Certificate
2001-05-03
2002-08-06
Poon, Peter M. (Department: 3643)
Ammunition and explosives
Cartridges
Practice projectile type
C102S529000, C102S447000, C102S446000, C102S498000
Reexamination Certificate
active
06427600
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to blank cartridges, particularly those used for training in conjunction with simulators and war games. More especially, the invention relates to a blank cartridge that will cycle most known types of self loading small calibre guns without the use of external adapters or the release of toxic gases and debris.
The object of a blank cartridge is to cycle self loading guns, preferably without allowing any dangerous particles or emissions to leave the barrel of the gun.
However, presently, all known blank cartridges suffer several disadvantages. Firstly, without the benefit of a bullet sited at the front of the cartridge, the blank cartridge often feeds through and jams the internal mechanics of the gun.
Furthermore, to develop the back pressures required to operate the gun's reloading mechanism, special blank firing adapters are usually required. These adapters spoil the balance and handling of a gun.
It is also known that conventional blank cartridges emit toxic gases and debris from the barrel of the gun after firing, are limited in power and therefore are only suitable for a small number of gun types and calibres.
SUMMARY OF THE INVENTION
It is an object of the present invention to solve the aforementioned problems by providing a blank cartridge that will cycle most known types of self loading small calibre gun without the use of external adapters.
Accordingly, in a first aspect, the invention provides a blank pyrotechnic cartridge for use in a firearm, the cartridge comprising a cartridge casing having a bullet-like projection extending forwardly therefrom, the bullet-like projection being retractable through an opening in the casing when the cartridge is fired, the cartridge being axially expandable in a rearwards direction in use to move the breechblock of a firearm to recycle the firearm, the cartridge optionally having sealing means for preventing propellant gases from escaping through the opening upon firing.
In another aspect, the invention provides a blank cartridge (e.g. a pyrotechnic cartridge) comprising a cartridge casing having a bullet-like projection extending forwardly therefrom, the bullet-like projection being retractable through an opening in the casing when the cartridge is fired, sealing means being provided for preventing propellant gases from escaping through the opening upon firing; the cartridge being axially expandable in a rearwards direction in use to move the breechblock of a firearm to recycle the firearm.
In the cartridges of the invention, the expandable cartridge casing can comprise a piston portion slidably received within a sleeve portion. For example, the cartridge casing can have a nose portion, the sleeve portion extending rearwardly of the nose portion. The bullet-like projection can be connected to or formed integrally with the piston portion and, in one embodiment, the piston has a hollow rear portion from which the bullet-like projection extends forwardly. The hollow rear portion can contain a pyrotechnic composition.
In one preferred embodiment, the invention provides a blank cartridge including a sleeve extending rearwardly from a nose portion, and a piston slidably disposed within the sleeve; the piston having at its forward end a spigot slidably received in a channel through the nose portion and extending forwardly of the nose portion, the piston having at its rearward end a chamber containing a pyrotechnic composition; an expansion chamber being provided within the sleeve between the piston and the nose portion, one or more gas channels being provided between the pyrotechnic composition in the piston and the expansion chamber; whereupon after ignition of the pyrotechnic composition, expanding gas passing through the one or more gas channels into the expansion chamber moves the piston rearwardly in the sleeve, the rearward movement of the piston causing the gun to recycle.
Preferably, the piston is hollow and one or more gas channels are provided between the hollow interior of the piston and the expansion chamber.
Accordingly, in a particularly preferred embodiment, the invention provides a blank cartridge including a sleeve extending rearwardly from a nose portion, and a hollow piston slidably disposed within the sleeve; the piston having a spigot slidably received in a channel through the nose portion and extending forwardly of the nose portion; an expansion chamber being provided within the sleeve between the hollow piston and the nose portion, one or more gas channels being provided between the hollow interior of the piston and the expansion chamber; whereupon after ignition, expanding gas passing into the expansion chamber moves the piston rearwardly in the sleeve, the rearward movement of the piston causing the gun to recycle.
The expansion chamber can be defined by a circumferentially disposed inner surface of the sleeve, a generally axially facing surface of the piston and a generally axially facing surface of the nose portion. The expansion chamber can be, for example, of generally annular configuration, surrounding an inner end of the spigot.
In one preferred embodiment, the spigot is sealed within the channel through the nose portion by sealing means, for example circumferential sealing means such as an ‘O’-ring, sited in a circumferential recess around the spigot. This prevents or minimises the escape of gases and other emissions from the barrel of the gun after firing.
The spigot typically is of a length such that after ignition,, all or the greater part of its length is withdrawn into the nose portion as the cartridge is expanded. This can be achieved for example by connecting the spigot to that portion of the expanding cartridge casing which is thrown rearwardly upon ignition.
The maximum extent of expansion of the cartridge casing is chosen such that when fully expanded, the cartridge can still be ejected from the gun in the normal way.
In yet another aspect, the invention provides a method of feeding blank ammunition into the barrel of a gun comprising the step of loading the gun with a blank cartridge as hereinbefore defined.
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Copier F. Chad
Lahive & Cockfield LLP
Poon Peter M.
LandOfFree
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