GB1594017A - Automatic guns - Google Patents

Description

(54) IMPROVEMENTS IN OR RELATING TO AUTOMATIC GUNS (71) We, KABUSHIKI KAISHA KAWA- GUCHIYA HAYASHI JUHO KAYAKU-TEN, a Japanese Company, of No. 3,4-chome, Muromachi, Nihonbashi, Chuo-ku, Tokyo, Japan, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement :- This invention relates to an automatic gun comprising a gun barrel mounted on a receiver accommodating a breechblock assembly, and a gas operating device for releasing the breechblock assembly on firing the gun. In particular, the invention relates to an automatic gun including a device which utilises the gas pressure generated by the burning gun-powder (or the like) on firing a cartridge to effect unlocking of the breechblock to allow rearward (relative to the muzzle) movement thereof.

In this Specification, the terms'forward' and'rearward'are used to mean respectively towards the muzzle of the barrel and towards the stock.

According to the invention there is provided an automatic gun comprising a gun barrel mounted on a receiver accommodating a breechblock assembly, and a gas operating device for automatically releasing the breechblock assembly on firing the gun, which device comprises an action bar mounted externally of the gun barrel to extend into the receiver whereby rearward movement (as defined herein) of the action bar further into the receiver releases the locking of the breechblock assembly thereby allowing said breechblock assembly to move rearwardly, the device further comprising a cylinder adapted to receive explosion gases, the cylinder being open rearwardly and formed as a part of or secured to the gun barrel, the forward end portion of the action bar being formed as a piston, slidably located in the cylinder and not restrained by the open end of the cylinder, and the rearward end portion of the action bar extending through a guide hole formed in the receiver to be positioned adjacent the front face-of the breechblock in a normal operation position thereof and having a stop on the rearward end portion which co-operates with a surface surrrounding the guide hole to limit the rearward movement of the action bar in firing the gun.

Preferably a sleeve threaded into a bore in the receiver provides said guide hole and said surface surrounding the guide hole, the sleeve being adjusted axially on rotation thereof.

Preferably the stop on the rearward end portion of the action bar is an annular shoulder or flange.

By way of example only a specific embodiment of an automatic gun according to this invention will now be described with reference to the accompanying drawings, in which :- Figures 1 and 2 are side views, partly in cross-section, of one embodiment of an automatic gun provided with a gas operation device constructed in accordance with the present invention, Figure 1 showing the arrangement of the gas operation device in its non-operated state, while Figure 2 shows the arrangement in its operated state; Figure 3 is a view taken along line A-A in Figure 1 ; and Figure 4 is a cross-sectional view taken along line B-B in Figure 1.

Referring to Figures 1 and 2, there is shown a gun barrel 1, a receiver housing 2 and a breechblock assembly 3. The breechblock 3 comprises in combination a breechblock upper body 3a and a breechblock slider 3b, which parts are relatively movable, and a locking block 3c freely insertable into and retractable from an opening in the breechblock upper body 3b. The receiver housing 2 has a bore 2b for receiving the gun barrel 1 (Figures 3 and 4) and a hole 2c for receiving the cartridge magazine 6, as well as a bore 2a serving as a guide hole for an action bar 7.

A cylinder 4 is fixedly secured to the gun barrel 1 approximately mid-way therealong in the axial direction, the cylinder 4 being in communication with the interior of the gun barrel 1 through a gas hole 5. The front end portion of the action bar 7 is of enlarged diameter and carries a piston ring 4', effecting a seal between the enlarged end of the action bar and the cylinder 4, allowing the action bar to slide therein.

The rearward end of the action bar is of reduced diameter and passes through the guide hole 2a in the receiver housing 2, so that the bar end is positioned at the front face of the breechblock slider 3b included in the breechblock 3 held in the stationary state shown in Figure 1. A stepped shoulder portion 8a of the action bar 7 is so configured as to be engageable with a flange portion la of the gun barrel 1. In other words, the flange portion la of the gun barrel 1 serves as an end stop to restrict the'axial displacement of the action bar 7 to a predetermined length I as shown in Figure 1. A fixing bracket 10 is arranged to allow a cartridge magazine 6 to be removably mounted on the gun barrel 1.

The sequence of operation of the gun shown in the drawings is as follows. Prior to the firing of a cartridge, the action bar 7 (which is of one-piece construction) is urged against the breechblock slider 36 of the breechblock assembly 3 so as to be positioned as shown in Figure 1. The breechblock assembly 3 is locked so that the breechblock 3a blocks the abutting surface of the gun barrel 1 against the breechblock assembly 3 with the locking block 3c being in engagement with the recess lc of the gun barrel 1.

When the cartridge is fired, the gas pressure of a predetermined value is introduced into the cylinder 4 so that the action bar 7 is moved rearwardly by the force of the gas pressure. Thus, the rearward end portion of the action bar 7 causes a rearward movement of the breechblock slider 3b and, when the rearward stroke thereof exceeds a predetermined amount, the locking by the locking block 3c is released so that the rearward movement of the entire assembly of the breechblock assembly 3 is effected. On the other hand, the rearward movement of action bar 7 is restricted by the engagement of the stepped shoulder portion 8a with the flange portion la of the gun barrel 1 so that it is stopped at the position shown in Figure 2. When the breechblock assembly 3 moves forwardly, the action bar 7 is restored to its initial position.

In the sequence of operations as described above, when the value of the gas pressure introduced into the cylinder 4 is large, the breechblock assembly 3 might collide against the rearward bottom portion of the receiver housing 2, resulting in possible damage. Therefore, the enlarged diameter portion of the action bar 7 is made relatively long while the reduced diameter portion thereof is made relatively short, thereby permitting the force urging the breechblock assembly 3 rearwardly to be reduced.

The construction described above is far simpler than the prior art gas operating devices for reloading guns. The action bar 7 can be easily interchanged when the gun barrel 1 is removed from the receiver housing 2, and proper rotational operation of the breechblock can be ensured by using an action bar which has its permissible axial displacement appropriately adjusted to a particular cartridge having a known gas pressure characteristic thereby broadening the range of application of an automatic gun.

As is clear from the construction shown in the drawings, the element of the gas operating device, except thé breechblock assembly 3, comprises an integrally-formed rod-like action bar, which is not subjected to bending moments in operation of the gas operating device. Therefore there is considerable freedom in the choice of a suitable material, strength and the like, and the design is simplified.

Furthermore, the means for restricting the axial displacement of the action bar to a predetermined amount can be constructed by threading a sleeve into the guide hole of the receiver housing, the action bar through the sleeve and the action bar being arrested by engagement of the stepped shoulder portion of the action bar with the front end face of the sleeve. This construction permits the position of arresting to be freely adjustable in a stepless manner by merely turning the threaded sleeve to a required position.

Claims (4)

WHAT WE CLAIM IS :-

1. An automatic gun comprising a gun barrel mounted on a receiver accommodating a breechblock assembly, and a gas operating device for automatically releasing the breechblock assembly on firing the gun, which device comprises an action bar mounted externally of the gun barrel to extend into the receiver whereby rearward movement (as defined herein) of the action bar further into the receiver releases the locking of the breechblock assembly thereby allowing said breechblock assembly to move rearwardly, the device further comprising a cylinder adapted to receive explosion gases, the cylinder being open rearwardly and formed as a part of or secured to the gun barrel, the forward end portion of the action bar being formed as a piston, slidably located in the cylinder and not restrained by the open end of the cylinder, and the rearward end portion of the action bar extending through a guide hole formed in the receiver to be positioned adjacent the front face of the breechblock in a normal operation position thereof and having a stop on the rearward end portion which co-operates with a surface surrounding the guide hole to limit the rearward movement of the action bar in firing the gun.

2. An automatic gun according to claim 1 wherein a sleeve threaded into a bore in the receiver provides said guide hole and said surface surrounding the guide hole, the sleeve being adjusted axially on rotation thereof.

3. An automatic gun according to claim 1 or claim 2 wherein the stop on the rearward end portion of the action bar is an annular shoulder.

4. An automatic gun substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.