Ordnance – Practice barrels
Reexamination Certificate
1999-05-13
2001-08-21
Johnson, Stephen M. (Department: 3641)
Ordnance
Practice barrels
C089S014050, C089S163000, C042S077000
Reexamination Certificate
active
06276252
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to the field of firearms and provisions for modifying semi-automatic firearms for training purposes. In particular, it relates to reliable chambering of ammunition in blow-back firearms that have been modified to fire low-energy ammunition.
BACKGROUND TO THE INVENTION
In military and police firearms applications almost all of the ammunition consumed is used in training. For some training purposes, however, normal ammunition is not adequate. An alternative type of known training ammunition, represented by U.S. Pat. No. 5,359,937 (adopted herein by reference), fires a low-mass projectile relying on a special, low-energy cartridge designed to provide cycling of suitably-modified, recoil-operated automatic weapons.
An advantage of the low-energy training ammunition is that it has a shorter range and lower penetration capacity than standard ammunition. This permits use of smaller, less secure firing ranges as training facilities. If standard ammunition were accidentally employed in these facilities, unexpected dangers would arise from the increased striking power and range of standard ammunition.
The weapon modifications required to permit cycling while firing low-energy training ammunition generally include replacing or modifying the barrel and sometimes replacing or adding one or two other components, depending on the weapon involved. These modifications also serve to increase safety. For example, in 9 mm automatic firearms, the calibre of the substitute training barrel may be smaller than the diameter of the projectiles in standard 9 mm ammunition. If an attempt is made to chamber a standard round in such a training-adapted firearm, the barrel will not normally admit entry of the standard projectile. This ensures that such modified weapons cannot fire standard, live ammunition.
The low-energy cartridge represented by U.S. Pat. No. 5,359,937, in combination with a substitute training barrel, allows normal recoil and cartridge case ejection through a blow-back action. Such a system, when firing appropriate marking cartridges, makes for effective close-range, force-on-force training. This system enhances the realism and training value of interactive scenario tactical training because it allows trainees to use their service weapons in a representative manner in exercises simulating, for example, counter-terrorism, close quarters combat, trench clearing, fighting in wooded areas, urban fighting, and protection of dignitaries.
When firing standard ammunition, with its abundant associated energy, it is necessary in many weapons, particularly hand guns, to lock the barrel to the slide during the beginning of their rearward motion for a period long enough for the projectile to exit the barrel muzzle while the breech is still closed. This allows the chamber pressure to drop before the breech opens to eject the spent cartridge case. A locking mechanism couples the slide and barrel together for the first portion of the recoil, and then releases the slide, usually with the aid of a cam. Thus, in such normal weapons, the barrel recoils, at least partially, with the slide. Upon unlocking, the slide continues its rearward travel while the barrel stops in the proper position to receive the next round from the magazine to be chambered by the slide as it returns to its in-battery position.
In a training barrel it is necessary to omit this breech-lock mechanism and, by so doing, the recoil action becomes pure blow-back of the slide only. This is because there is not sufficient energy in low-energy training cartridges to precipitate sufficient recoil to unlock the barrel and the slide in their standard configurations. A training barrel of the type addressed by this invention is similar in most aspects to the standard service barrel for a particular pistol which normally relies on a barrel locking mechanism, but is modified, in part, by removing the locking mechanism that holds the barrel and slide together for the first portion of the recoil cycle. Thus, upon firing, the slide is free to move rearwards from its in-battery position unencumbered by the barrel. By so doing, maximum energy is transferred to the slide, thereby contributing to reliable weapon function.
In some 9 mm pistols, however, after the locking mechanism has been removed so that the weapon can fire low-energy ammunition as represented by U.S. Pat. No. 5,359,937, the training barrel does not or cannot move rearward far enough after firing to be in its proper position to receive the next round to be chambered. This happens precisely because the barrel is no longer locked to the slide, which would normally carry the barrel to the correct position before unlocking and leaving it there.
One way to solve this problem is described in PCT Application No. PCT/CA97/00174 (filed Mar. 14, 1997) for semi-automatic pistols such as the Walther P-5 in which the recoil spring(s) are not positioned beneath the barrel. In such instances, a spring-loaded Barrel Positioning Mechanism may be attached to one or more of the lugs of the training barrel, thereby ensuring that the barrel is moved sufficiently rearward when the breech is open to reliably chamber the next cartridge to be fired.
In other automatic pistols, however, the location of the recoil spring under the training barrel precludes such a solution for correctly locating the barrel for reliable chambering of the next cartridge to be fired. In some instances, as in the present invention, the training barrel is fixed with respect to the frame (receiver). It is, therefore, an object of this invention to provide a training barrel system for this class of firearms that will ensure the proper chambering of the next cartridge to be fired.
The concept of converting a pistol so that it can fire low-energy ammunition, as represented by U.S. Pat. No. 5,359,937, requires replacing the service barrel by a training barrel without modifying the slide or the frame. In this way, the weapon can be rapidly reconverted to fire live ammunition again by removing said training barrel and reinstalling said service barrel. Other minor modifications may be necessary (e.g., to the firing pin) but they, too, can be quickly reverted to their original configurations. It is, therefore, another objective of this invention to provide a training barrel system for this class of training firearm that will allow quick and easy assembly of the training barrel without modification to either the frame or the slide.
The invention in its general form will first be described, and then its implementation in terms of specific embodiments will be detailed with reference to the drawings following hereafter. These embodiments are intended to demonstrate the principal of the invention and the manner of its implementation. The invention in its broadest and more specific forms will be further described, and defined, in each of the individual claims which conclude the specification.
SUMMARY OF THE INVENTION
This invention is directed to certain semi-automatic pistols, especially those where the recoil spring is located under the barrel, which are adapted to fire low-energy training ammunition by the substitution of a training barrel that omits the breech-lock feature normally present and is fixed to the frame. It provides a system for ensuring proper chambering of ammunition by fitting a non-integral removable ramp extension to the breech end of the training barrel, such extension extending rearward towards the top of the magazine in such a fashion as to allow smooth passage from the magazine to the chamber of the next round to be fired. Without this ramp extension, the barrel breech would be too far forward from the top of the magazine and the incoming cartridge would not necessarily enter the chamber cleanly, hence provoking a weapon jam whenever such misalignment should occur.
According to the invention, a firearm is provided with a slide and a training barrel which at no time are locked together during the firing cycle. The training barrel, which is fixed with respect to the frame, is provided w
French David J.
Johnson Stephen M.
SNC Technologies Inc.
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