Firearms – Barrels
Reexamination Certificate
2002-04-05
2003-04-08
Eldred, J. Woodrow (Department: 3644)
Firearms
Barrels
C089S001410, C089S028050, C089S126000
Reexamination Certificate
active
06543174
ABSTRACT:
TECHNICAL FIELD
The invention relates to firearms and weapons for firing projectiles. In particular, the present invention relates to barrel assemblies for guns such as firearms and larger calibre weapons.
This invention has particular, but not exclusive, application to handguns including shotgun type firearms and to other weapons which utilize barrel assemblies such as described in the inventor's earlier International Patent Applications Nos. PCT/AU94/00124 and PCT/AU96/00459.
Such barrels each have a plurality of projectiles stacked axially within the barrel together with discrete selectively ignitable propellant charges for propelling the projectiles sequentially through the muzzle of the barrel and the sealing engagement between projectiles and barrel being such as to prevent rearward travel of the ignited propellant charge to trailing propellant charges. These barrels will be referred to hereinafter as of the type described.
BACKGROUND ART
This invention aims to alleviate perceived shortcomings in conventional weapons such as shotguns which fire a collection of round pellet like shot randomly oriented in the cartridge, which when fired exit from a relatively large bore barrel in a random orientation and at a relatively slow muzzle velocity.
The shot immediately disperses to cover a relatively large target zone. This effect is useful but the effective range of the shot is very short. Shotguns also require reloading between shots and this reduces their effectiveness.
Handguns such as pistols also have significant limitations for many reasons including the limited number of shots which may be contained in the weapon and the relatively slow rate of fire available. However they are very portable and concealable and this makes them very useful.
In the earlier filed International Patent Application No. PCT/AU96/00459 there is described a wedging action between the head part and the anvil part that effects a seal between a projectile and the bore of the barrel behind the propellant charge being fired. This seal ensures minimum loss of propellant past the projectile and maintains a seal between the next projectile and the barrel so that the ignited propellant does not pass the next remaining projectile and cause ignition of the propellant charge therebehind.
While no jamming of rounds has been experienced to date it is considered that this possibility needs to be addressed, especially if high barrel pressures in the order of 60,000 psi plus are to be utilised. The present systems are intended to operate with a maximum internal pressure in the order of 40,000 psi chamber pressure.
We have now found a barrel assembly that provides improved safety in that risk of catastrophic failure of the barrel assembly is reduced in the event of a “hang-fire”. In the event of a round jamming or a projectile other than the leading projectile being fired there is a risk that the pressure in the barrel may increase as a result of detonated propellant charge(s) such that the barrel itself may explode.
DISCLOSURE OF INVENTION
In one aspect, the present invention provides a barrel assembly comprising a plurality of projectiles axially disposed within a barrel and associated with discrete selectively ignitable propellant charges for propelling the projectiles from the barrel wherein said barrel includes at least one pressure relief valve associated with a chamber in which a propellant charge is ignited.
In a preferred configuration the pressure relief valve vents into a bypass passage that exhausts in the direction of fire of the barrel assembly. In such a configuration there may be an exhaust that is parallel to the barrel assembly. Alternatively, the exhaust may be coaxial with and of larger diameter to the barrel. The exhaust may extend the length of the barrel, may extend beyond the muzzle of the barrel or may terminate prior to the muzzle of the barrel.
The pressure relief valve may be in the form of a plug or bung fixed into the barrel such that once the barrel pressure reaches a selected limit the plug or bung is ejected from the aperture into which it is fixed. Alternatively, the pressure relief valve may be in the form of a rupturable section of the barrel that is formed from a material that is selected to fail once the barrel pressure reaches a selected limit.
Preferably the barrel assembly includes a shielded cover for retaining the any ejected component from the pressure relief valve or at least preventing such a component from becoming a safety issue. For instance an ejected plug or bung could become a lethal projectile if ejected in an unrestrained manner. Similarly, any debris from a rupturable section of barrel may become a dangerous projectile that may be ejected laterally from the barrel. As such, in a weapon system, laterally fired projectiles would be unexpected and be a considerable risk. The shielded cover may be in the form of an armour-plated cover, a pneumatic chamber, a damped receptacle such as an oil filled reservoir.
A pressure relief valve may be positioned in the barrel adjacent each chamber in which a propellant charge is detonated. Alternatively, depending on the structural properties of the barrel, the risk of catastrophic failure may be significant only if a number of propellant charges are detonated in the confined barrel. In such configurations the pressure relief valves may be positioned along barrel and spaced so as to associate with every second, third or more propellant charges.
The present invention has particular application to barrel assemblies of the type described in International Patent Application Nos. PCT/AU94/00124 and PCT/AU96/00459. Such barrel assemblies include a barrel; a plurality of projectiles axially disposed within the barrel for operative sealing engagement with the bore of the barrel, and discrete propellant charges for propelling respective projectiles sequentially through the muzzle of the barrel.
The projectiles may be round, conventionally shaped or dart-like and the fins thereof may be offset to generate a stabilising spin as the dart is propelled from a barrel that may be a smooth-bored barrel.
The projectile charge may be in the form of a solid block and assist in operatively spacing the projectiles in the barrel. Alternatively, the propellant charge may be encased in metal or other rigid case which may include an embedded primer having external contact means adapted for contacting an pre-positioned electrical contact associated with the barrel. For example the primer could be provided with a sprung contact which may be retracted to enable insertion of the cased charge into the barrel and to spring out into a barrel aperture upon alignment with that aperture for operative contact with its mating barrel contact. If desired the outer case may be consumable or may chemically assist the propellant burn. Furthermore an assembly of stacked and bonded or separate cased charges and projectiles may be provided for reloading a barrel.
Each projectile may include a projectile head and extension means for at least partly defining a propellant space. The extension means may include a spacer assembly that extends rearwardly from the projectile head and abuts an adjacent projectile assembly. Such an extension means may assist the detent in the barrel in supporting the projectiles in position within the barrel when a leading charge is fired.
A spacer assembly may extend through the propellant space and the projectile head whereby compressive loads are transmitted directly through abutting adjacent spacer assemblies. In such configurations, the spacer assembly may add support to the detent and extension means. The extension means may be a thin cylindrical rear portion of the projectile head. Furthermore the extension means may form an operative sealing contact with the bore of the barrel to prevent burn leakage past the projectile head.
The spacer assembly may include a rigid collar that extends outwardly to engage a thin cylindrical rear portion of a malleable projectile head in operative sealing contact with the bore of the barrel. Thus axially
Eldred J. Woodrow
Metal Storm Limited
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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