Ammunition and explosives – Cartridges – Practice projectile type
Reexamination Certificate
1999-07-12
2001-01-30
Jordan, Charles T. (Department: 3641)
Ammunition and explosives
Cartridges
Practice projectile type
C102S444000, C102S445000, C102S446000, C102S430000, C102S464000, C102S469000, C102S470000
Reexamination Certificate
active
06178889
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to the field of ammunition, and it particularly relates to low impulse cartridges. More specifically, the present invention relates to a low impulse telescoping cartridge for use in automatic weapon systems such as the 40 mm MK19 Grenade Machinegun, though the inventive concept is applicable to any caliber of weapon and ammunition.
2. Description of Related Art
An automatic weapon such as the 40 mm MK19 Grenade Machinegun is typically actuated by the direct blowback of the cartridge case against the bolt upon expansion of the propellant gas during the time between cartridge ignition and projectile exit from the barrel. The MK19 Grenade Machinegun is designed to function when firing 40 mm cartridges with a cartridge impulse of approximately 13 to 15 pound-seconds. Reduced cartridge impulses provided by lower mass projectiles and/or reduced chamber pressure will result in reduced energy transferred to the bolt. Consequently, the weapon cyclic rate and reliability will be adversely affected. Exemplary low impulse cartridges that produce much lower impulse levels than required to function the MK19 Grenade Machinegun in the fully automatic mode include blanks, limited range training cartridges, and non-lethal cartridges.
One attempt to achieve reliable weapon function by including a telescoping cartridge case and piston configuration is described in U.S. Pat. No. 5,359,937 to Dittrich. The firearm barrel in Dittrich requires a chamber with an annular step at its forward end or a similar feature for the piston to push against. However, many conventional weapons, including the MK19 Grenade Machinegun do not have such a feature and it would be quite a laborious and expensive undertaking to retrofit the Dittrich design in such conventional weapons.
Therefore, there is a great and still unsatisfied need for a low impulse cartridge which is forced against the rear surface (or breech) of the barrel particularly when the firearm is set in an automatic mode.
SUMMARY OF THE INVENTION
One feature of the present invention is to satisfy this long felt need, and to provide a low impulse cartridge for use in a conventional automatic weapon systems such as the 40 mm MK19 Grenade Machinegun.
Another feature of the present invention is to provide an ammunition configuration that accelerates a bolt to the rear independently of the impulse generated from launching the projectile. This allows for the launching of low velocity and/or low mass projectiles (or payloads such as non-lethal multiple rubber balls, bean bags, foam batons, wood batons, sponge grenades, flash bang projectiles, limited range training projectiles, low cost training projectiles, etc.), and the firing of blank cartridges while functioning the MK19 Grenade Machinegun or other firearms in a fully automatic mode.
A further feature of the present invention is to provide a fully automatic weapon function without requiring changes to the weapon itself, while permitting effective firing of reduced velocity and/or reduced mass projectiles.
These and other features and advantages of the invention are achieved by a low impulse, telescoping cartridge for limited range training projectiles, low cost training cartridges, non-lethal projectiles/payloads, blank cartridges, and other applications.
The cartridge is comprised of a piston, a link, and a case in which a primer is fitted. The cartridge collapses during chambering to allow for the link movement relative to the base of the cartridge case during chambering, and for expanding the case during the weapon powering (or firing) stage of operation.
The cartridge provides the exterior cartridge characteristics required to feed through the weapon and chamber prior to firing. The telescoping cartridge case includes a shoulder or boss which is positioned under the link to provide a cartridge stop against the rear of the barrel, and through which the reaction loads are transmitted to counteract the loads applied to the bolt during rearward acceleration of the bolt.
In the case of the MK19 Grenade Machinegun, the shoulder is designed to allow the link to move rearward for a portion of the travel distance required between the link and the cartridge base. The case telescopes for the remainder of the rearward travel distance required to reach the fire (e.g. battery) position. Upon firing, the expanding propellant gases force the cartridge and piston to telescope open, accelerating the bolt rearward and cycling the weapon. A portion of the propellant gases is bled through orifices to propel the payload from the barrel. Alternatively, a second separate propellant charge may be used to launch the payload from the barrel at the desired energy level.
The operation of the 40 mm MK19 Grenade Machinegun using the cartridge of the present invention is as follows: The cartridge travels through the weapon feed mechanism. The outside configuration of the cartridge and the position of the link is preferably constrained to that of conventional ammunition in order to be compatible with the weapon. The link and cartridge are restrained during the delinking operation and cartridge pickup as the bolt reaches the battery position. As the bolt is returned rearward, the cartridge is cammed down the bolt face into alignment with the barrel. As the bolt moves forward to the battery position, the cartridge is chambered.
During chambering, the link moves relative to the base of the cartridge to allow the bolt to reach the fire position. This is accomplished by the cartridge telescoping alone or in combination with the link movement. The shoulder under the link provides the surface through which reaction loads are transmitted to the barrel. The shoulder provides the means for telescoping the cartridge to the closed position during chambering. Upon firing, the cartridge is forced to telescope open by the expanding propellant gases. Reaction loads are applied to the barrel through the shoulder and through the base of the cartridge to the bolt. The energy imparted to the bolt accelerates the bolt rearward and cycles the weapon.
The present invention enables the practical and efficient use of low impulse ammunition in an unmodified weapon such as the MK19 Grenade Machinegun. This design is enabled, at least in part, by the ability of the present cartridge to telescope closed to allow for the relative movement between the link and the base of the cartridge. Another important feature of the present cartridge is the presence of the shoulder under the link for transmitting reaction loads to the rear of the barrel.
In one embodiment, the secondary propellant charge can be used as an alternative to bleeding propellant gases from the primary propellant charge, in order to accelerate the projectile.
REFERENCES:
patent: H114 (1986-08-01), Quintavalle
patent: 3744420 (1973-07-01), Barr
patent: 4686905 (1987-08-01), Zsabo
patent: 5359937 (1994-11-01), Dittrich
patent: 5677505 (1997-10-01), Dittrich
Jordan Charles T.
Moran John F.
Sachs Michael C.
Semunegus Lulit
The United States of America as represented by the Secretary of
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