GB2043845A - Firearm - Google Patents

Abstract

A self-loading and/or automatic firearm in which all the parts which are stressed during firing are formed in a subassembly which can be located in a light-weight, non-stressed receiver. The sub-assembly includes a bolt 6 slidably mounted on one or more elongate frame members 2 rigidly secured to an end reaction plate 3 and to a breech block 4, the barrel 15 being fixed onto the breech block. Reaction take-up springs 8 are compressed between the bolt and end reaction plate. The sub-assembly may be removably located in the receiver 20 through an aperture in the butt region of the receiver. The receiver can be made of a material which is not as strong or heavy as that used normally for firearm bodies because unlike the latter the receiver is not subject to stress during firing. <IMAGE>

Description

SPECIFICATION Firearm This invention relates to self-loading and/or automatic firearms.

Known firearms generally have a body the outside of which forms the exterior of the firearm and inside the body there are bearing surfaces for the moving parts of the action of the firearm, i.e.

the bolt, to slide on. The body therefore has to be made of a rigid material and be of sufficient strength and mass to make it capable of withstanding the stresses imposed on the bearing surfaces and the body during operation. The body of a firearm is therefore usually substantial and heavy.

A body made of a lightweight material is unlikely to be strong enough or if a sufficiently strong light-weight material is used it is likely to be very expensive or incompatible for use with the moving parts of the mechanism which are commonly made of steel.

According to the present invention, there is provided a self-loading or automatic firearm comprising a receiver the sub-assembly adapted to be located in the receiver, the sub-assembly comprising at least one elongate frame member rigidly secured at its ends respectively to an end reaction plate and to a breech block having or adapted to have a barrel fixed to it, a bolt siidably mounted on the elongate frame member, one or more compression springs located between the end reaction plate and the bolt for absorbing the reaction movement inertia of the bolt, and ejector means for ejecting a spent cartridge and operable by movement of the bolt, the-sub-assembly forming a structure which is capable of withstanding the stresses produced during firing, and the receiver being made of a lightweight material constituting a non-stressed casing and having a trigger assembly and means for supporting magazine or belt of cartridges.

Preferably, the sub-assembly includes two parallel elongate frame members in the form of circular cross-section rods and the bolt has two corresponding through holes through which the rods extend. These provide adequate support for the bolt and satisfactory bearing surfaces along which the bolt is guided with little frictional resistance. It also provides a imple frame structure which is inexpensive and easy to make.

However, in alternative embodiments there may be a single elongate frame member having a noncircular cross-section, or there may be more than two rods, for example three or four.

The rods may simpiy be welded at each end to the end reaction plate and to the breech block, or they may be fixed by screw-threaded connections.

The or each compression spring conveniently comprises a coil spring located around the elongate rod, the end face of the bolt, which is nearer to the end reaction plate, having a corresponding counterbore to provide a longer travel path for the bolt and to prevent the compression spring from being over compressed.

The ejector means conveniently comprises an ejector pin projecting forwardly from the end reaction plate and an extractor claw on the bolt.

The bolt may have a hole through which the ejector pin extends.

The receiver is preferably made of a plastics material which is strong enough to support the sub-assembly and to stand up to the normal stresses of handling and usage of the firearm but it need not be strong enough to take any of the actuai stresses occurring during firing because these are all taken by the sub-assembly.

The receiver may be designed to have the subassembly inserted forwardly through an aperture in the back of the butt region, and fixed therein; for example the muzzle of the barrel may be screw-threaded, and the barrel arranged to project through a barrel cover of the receiver so that a nut can be screwed onto the muzzle to tighten and hold the sub-assembly in the receiver by, for example, a shoulder in the receiver abutting the breech block of the sub-assembly.

The invention may be carried into practice in a number of ways but one specific embodiment will now be described, by way of example, with refrence to the accompanying drawings, in which: Figure 1 shows diagrammatically a perspective view of a firearm in accordance with the invention, and Figure 2 is a front view of the bolt of the firearm shown in Figure 1.

The firearm which is self-loading or automatic in operation comprises two partial assemblies, namely a sub-assembly of the working mechanism, or action, of the firearm with the barrel and its ancillary features all of which are put under stress during firing-these parts being shown in full lines-, and a receiver constituting the outside non-stressed cover of the firearm this being shown in dash-dot lines.

The sub-assembly incorporating the action comprises a rigid frame of two parallel, circular cross-section rods 2 each secured, by welding or by screw-threaded connections, at one end to an end reaction plate 3 and at the other end to a breech block 4. A bolt 6 having two corresponding holes 7 through which the rods 2 extend is capable of sliding along the rods 2 between the breech block 4 and the end reaction plate 3, movement towards the latter causing two coil springs 8 located around the rods 2 to be compressed. The end face of the bolt 6 nearer to the end reaction plate 3 has counterbores receiving the springs 8 to prevent the springs from being over compressed and to provide a long path of travel of the bolt 6.

Projecting forwardly from the end plate 3 is an ejector pin 10 which projects part way towards the breech block 4 within a further hole 11 in the bolt 6. The ejector pin 10 and the hole 11 are arranged eccentrically in the bolt 6 as can be seen in Figure 2, for ejecting a spent cartridge as will be explained. The front face of the bolt 6 (seen in Figure 2) has a firing pin 12 and an extractor claw 14 which also serves for ejecting a spent cartridge.

To the front of the breech block 4 is attached a barrel 15 the muzzle end 17 of which has an external screw-thread engaged by a nut 1 8.

These parts making up the sub-assembly are all made of steel or other strong material to enable them to withstand the stresses which occur during firing.

The other partial assembly mainly comprises the receiver 20 which is a one- or two-piece moulding of lightweight plastics having a body portion 21, a barrel cover 22, a handle 23, a trigger assembly 24 including a sear which is not shown, and a magazine attachment, also not shown, for hoiding a magazine 26 of iive cartridges. Non of these parts is subjected to stress during firing of the firearm and they may therefore be made of less strong and/or lighter weight material provided they are strong enough to stand up to normal handiing, and wear and tear.

To assemble the sub-assembly of the working mechanism with the receiver 20, the subassembly is inserted into a hole 28 in the back of the butt region until the muzzle 1 7 extends out of the front end of the barrel cover 22 and an annular shoulder 29 inside the receiver body 21 abuts the front face of the breech block 4. the nut 18 is then screwed onto the muzzle 1 7 to tighten the assembly.

A cocking mechanism (not shown) is provided, for example on the top of the receiver.

In operation, the firearm is cocked by drawing the bolt 6 back against the force of the springs 8 and held in this position by the sear. A live cartridge will be located in the region behind the breech block 4. When the trigger mechanism 24 is operated the bolt 6 will be released by the sear and be projected forward by the force of the springs 8 until its front face contacts the cartridge which is thus stripped from the top of the magazine 26, the end of the cartridge is engaged by the extractor claw 14, and the cartridge is pushed forward into the breech 31; the bolt 6 strikes the end of the cartridge with its firing pin 12 causing the cartridge to fire.

The reactive force presses the bolt 6 back in the other direction until its recoil energy is absorbed by the recoil springs 8. The bolt 6 will not normally ever strike the end reaction plate 3; however, to avoid risk of damage if that should happen owing to unusual circumstances, a buffer disc may be attached to the back face of the bolt 6.

During the back travel of the bolt 6, the stationary ejector pin 10 will project through the front of the hole 11 in the bolt 6 and push the spent cartridge to one side with a tilting motion caused by the fact that the extractor claw 14 engages one side lip of the cartridge end.

At the end of its back travel, the bolt 6 will have compressed the spring 8 which then force the bolt 6 forwards again to initiate the next firing cycle, a fresh cartridge having moved automaticaíly into the breech region by the action of a spring within the magazine 26.

The firearm may be designed to fire repeatedly either automatically until the trigger is released or each time the trigger is pulled.

It will be appreciated that the action is very simple which not only makes it easy and cheap to manufacture but also makes it easy to clean and reliable in operation even if dirt does get into the mechanism; because the receiver takes no stress in firing it can bemade much more cheaply than can bodies of known firearms, from a suitable lightweight material. The basic concept therefore is the provision of all the stressed parts in a subassembly located in a non-stressed receiver.

Whilst the cross-section of the bolt 6, the end plate 3 and the breech block 4 is generally circular (the bolt 6 has a cut-away sector to reduce its weight), they may be other cross-sectional configurations, e.g. rectangular. Furthermore there may be more than two rods 2 though the number of rods should be few to keep the friction of the bearing surfaces on which the bolt 6 slides to a minimum and to provide as few parts as possible which can get clogged with dirt.

Furthermore, the arrangement by which the subassembly is fixed in the receiver may differ from that illustrated. Any suitable locating and securing arrangement may be used. Also, in place of the magazine feed, the firearm may be adapted to operate with a supply of cartridges in a belt.

Claims (14)

Claims

1. A self-loading or automatic firearm comprising a receiver and a sub-assembly adapted to be located in the receiver, the subassembly comprising at least one elongate frame member rigidly secured at its ends respectively to an end reaction plate and to a breech block having or adapted to have a barrel fixed to it, a bolt slidably mounted on the elongate frame member, one or more compression springs located between the end reaction plate and the bolt for absorbing the reaction movement inertia of the bolt, and ejector means for ejecting a spent cartridge and operable by movement of the bolt, the sub-assembly forming a structure which is capable of withstanding the stresses produced during firing, and the receiver being made of a lightweight material constituting a non-stressed casing and having a trigger assembly and means for supporting a magazine or belt of cartridges.

2. A firearm as claimed in claim 1, in which there are two or more parallel elongate frame members and the bolt has two or more corresponding holes through which the rods extend.

3. A firearm as claimed in claim 2, in which the rods and the holes in the bolt are of circular crosssection.

4. A firearm as claimed in claim 2 or claim 3, in which there is a respective coil compression spring located around each rod between the end reaction plate and the bolt.

5. A firearm as claimed in claim 4, in which the end face of the bolt, which is nearer to the end reaction plate, has a respective counterbore for each compression spring in which the compression spring is partially accommodated.

6. A firearm as claimed in any one of the preceding claims, in which the ejector means comprises an ejector pin projecting forwardly from the end reaction plate such that when the bolt has moved back under the reactive force after firing, the free end of the ejector pin projects forwardly beyond the front face of the bolt, and an extractor claw on the bolt for holding the rim of a cartridge.

7. A firearm as claimed in claim 6, in which the ejector pin extends through a hole in the bolt.

8. A firearm as claimed in any one of the preceding claims, in which the bolt, the end reaction plate and the breech block have generally circular cross-sections.

9. A firearm as claimed in any one of the preceding claims, in which the receiver is made of a plastics material.

10. A firearm as claimed in any one of the preceding claims, in which the receiver is adapted to have the sub-assembly inserted forwardly through an aperture in the back of the butt region, releaseable fixing means being provided to retain the sub-assembly in position in the receiver.

11. A firearm as claimed in claim 11, in which the releaseable fixing means is constituted by a screw-thread on the muzzle end of the barrel, which muzzle end projects through a barrel cover of the receiver so that a nut screwed onto the muzzle bears against the barrel cover and hold the sub-assembly in the receiver.

12. A firearm as claimed in claim 11, in which, when the sub-assembiy is fully inserted into the receiver, the breech block abuts a shoulder provided in the receiver, the breech block being pressed against the shoulder when the nut on the muzzle end is tightened, thereby to hold the subassembly rigidly in the receiver.

13. A firearm as claimed in any one of the preceding claims, provided with a cocking mechanism located on the top of the receiver.

14. A firearm substantially as specifically described herein with reference to the accompanying drawings.