Ordnance – Practice barrels
Reexamination Certificate
1999-07-26
2001-03-20
Johnson, Stephen M. (Department: 3641)
Ordnance
Practice barrels
C089S014500
Reexamination Certificate
active
06202533
ABSTRACT:
BACKGROUND OF INVENTION
This invention is related to BLANK FIRING ADAPTOR, U.S. Pat. No. 5,438,907 by George Reynolds and John Miller, but is equipped with a subcaliber barrel instead of a spigot, employs gas pressure multiplier system and fires bulleted cartridges or blanks.
Medium caliber automatic weapons such as the Mk19, 40 mm machinegun used by U.S. military forces require relatively expensive training ammunition because of the relatively large size of the ammunition used plus the fact that the Mk 19 is a machinegun. It is estimated there are 300,000 Mk 19's in active use in the U.S. military services. It is conservatively estimated that each gun is fired 100,000 rounds in training during the life of the weapon. Conventional training rounds cost approximately $15 each, resulting in a life cycle training cost for ammunition of $450 billion. Thus, the cost of adequate training is very high for this very effective weapon. Subcaliber devices which provide realistic training are well known for use in most small arms weapons, but until the present, none have been suitable for use with the Mk19 and similar weapons.
SUMMARY OF PRESENT INVENTION
The present invention provides for realistic training by firing relatively inexpensive subcaliber cartridges or blanks in reloadable adaptors. With the cost of the subcaliber device/blank firing adaptor at, say $500 each, the cost of the adaptor cases at $5 each and the cost of the subcaliber cartridge or blank cartridge at 25 cents each, the life cycle cost for firing 100,000 subcaliber rounds through 300,000 Mk19's is approximately $9.1 billion, as compared with $450 billion dollars with full caliber training rounds. Use of the subcaliber device will result in a 98% cost reduction for training ammunition compared to using the least expensive full caliber training rounds.
The subcaliber device/blank firing adaptor powers a blowback or recoil operated weapon so the weapon will function in normal automatic fire. All loading, firing, safety, and stoppage procedures normally performed by the gun crew are employed when using the sibcaliber device/blank firing adaptor.
Firing with the subcaliber device/blank firing adaptor approximates the feel and noise of firing full caliber service ammunition. The trajectory of the subcaliber projectile nearly duplicates that of fill caliber service ammunition. This closely matching trajectory is especially valuable when using subcaliber tracer projectiles so the soldier can become very familiar with the characteristics of time of flight and trajectory arc of service rounds while firing inexpensive subcaliber rounds.
The cartridge case adaptor which contains the subcaliber cartridge or blank cartridge is easily and rapidly reloadable by soldiers training in the field. Reloading is accomplished using a simple, hand operated fixture which is not part of this patent. Installation of the subcaliber device/blank firing adaptor requires no special tools and is performed by the gun crew in the field, requiring less than five minutes in the case of the Mk19 machinegun. All subcaliber device/blank adaptor components are low technology, require no exotic materials, and are inexpensive to manufacture. The blank firing adaptor uses standard, commonly issued conventional rifle/machinegun blanks.
In the three subcaliber device embodiments of the invention three different methods are used to multiply the force of the propellant gas above the straight blowback force of the projected area of the base of the projectile. In the blank firing adaptor embodiment, gas is trapped by a vented muzzle disc at the front of the subcaliber barrel to retain pressurized gas to apply sufficient force to operate the weapon.
In the first embodiment, instead of reaction of the propellant gas being only against the projectile, part of the reaction is transmitted from a primary booster area to the weapon frame though a subcaliber barrel inserted through the main gun barrel and anchored to the muzzle of the main gun barrel.
In the second embodiment, in addition to the reaction of the propellant gas against the primary booster area, as in the first embodiment, a secondary chamber with a secondary booster area is provided to trap gas to apply force for a longer period of time. Propellant gas is released from the subcaliber cartridge chamber into the secondary booster chamber when pressure in the subcaliber chamber exceeds the strength of the subcaliber cartridge case wall at the chamber vent, perforating the subcaliber cartridge case wall at the subcaliber chamber vent. In this embodiment, gas escaping into the secondary chamber of the adaptor pressurizes a larger area (e.g. ten to twenty times greater) than the projected bore area of the subcaliber cartridge projectile. Gas is trapped in the secondary booster by the restriction of the gas vent which admitted the highly pressurized gas from the subcaliber chamber, much as gas is trapped in the gas cylinder of a conventional gas operated gun mechanism.
The third embodiment is like the second embodiment except the secondary chamber is vented to the atmosphere to limit the operating force to that of the primary booster area by eliminating force (rather than adding force) from the secondary booster. This embodiment is required when a standard cartridge such as the 7.62 mm NATO is used, but which provides excess power with the Mk 19. It is desirable to use standard 7.62 mm machinegun ammunition due to its low cost and ready availability.
A fourth embodiment permits the subcaliber device to be converted into a blank firing adaptor related to U.S. Pat. No. 5,438,907 by the installation of a vented restrictor disc at the front of the muzzle of the subcaliber barrel. The vented restrictor disc sufficiently contains the blank generated pressurized gas to operate the weapon. Blank cartridges operate at such low pressure when operated with a large free volume, that the cartridge case wall will not perforate at the booster vent to release gas into the secondary booster chamber. The vented restrictor disc is retained by a vented muzzle cap which also serves as a bullet trap in case a bulleted cartridge is accidently fired when normally using blanks. If a rifle grenade launching cartridge, which is much more powerful than a blank, is accidently fired, the higher pressure of the grenade cartridge bursts the vented restrictor disc, preventing the high power of the grenade cartridge from damaging the gun mechanism. The vented restrictor disc is inexpensive and easily replaced.
In the first three embodiments the operating force of the subcaliber cartridge is multiplied above that available through straight blow-back by a factor equal to the ratio of the projected area of the bore of the subcaliber cartridge to the area of the total booster areas affected by the gas. This fully powers the weapon while using a cartridge less than {fraction (1/20)} the weight and {fraction (1/50)} the cost of the least expensive training cartridge the weapon was designed for. By adjusting the booster area(s), initial volume, length of power stroke, diameter of perforation, projectile weight and by selecting powder burning rate the subcaliber device and cartridge can be designed to launch a subcaliber projectile at the same velocity (or higher or lower) as the service projectile. Thus the trajectory of the service round can be closely duplicated provide realistic training. Tracer ammunition can be used where range conditions permit, or ball ammunition can be used where dry range conditions prohibit the use of tracers.
The total blowback force is equivalent to that generated by a full caliber service round, but the reaction is primarily against the gun itself through the subcaliber barrel and muzzle cap attached to the muzzle of the weapon barrel instead of reacting only against the projectile as in straight blow-back operation. In the case of the 40 mm Mk19 subcaliber device using a 1.300 inch diameter secondary booster area and firing a 0.308 diameter subcaliber bullet, the effective total blowback area is approximately 19 t
Miller John M.
Reynolds George L.
Reynolds S. Paul
Armalite Inc.
Johnson Stephen M.
Woodard Emhardt Naughton Moriarty & McNett
LandOfFree
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