US2788715A - Automatic loading firearms having a breech block temporarily held in locked position by a sliding system - Google Patents

Description

. 2,788,715 ORARILY HELD IN LDCKED POSITION BY A suomc svs'mu .April 16, 1957 m i -r AUTOMATIC LOADING FIREARMS HAVING A BREECH BLOCK TEMP Filed Feb. 9, 1951 m A TTURNEY United States Patent AUTOMATIC LOADING FIREARMS HAVING A BREECH BLOCK TEMPORARILY HELD IN LOCKED POSITION BY A SLIDING SYSTEM Marc Birkigt, Versoix, near Geneva, Switzerland, assignor to Brevets Aero-Mecaniques, S. A., Geneva, Switzerland, a society of Switzerland Application February 9, 1951, Serial No. 210,105 Claims priority, application Luxemburg February 18, 1950 1 Claim. (Cl. 89-190) The present invention relates to automatic loading firearms (this term including, in the following specification and claim, semi-automatic firearms the reloading of which takes place automatically but the firing of which is performed manually for every shot, fully automatic firearms firing by bursts and firearms capable of working either semi-automatically or automatically) in which the movable breechblock is held temporarily locked in position by a movable system capable, once the breechblock has reached the end of its forward stroke, of sliding with respect to said breechblock so as temporarily to prevent unlocking of the breechblock. And it is more especially concerned with automatic guns in which the sliding system is constituted by two longitudinal sliding bars disposed on either side of the breechblock inside the breech casing.

It is of interest, in firerams of this kind, to provide safety means capable of preventing accidental rebounding of this sliding system, because such a rebounding might, it of sufficient amplitude, bring the sliding system into a position such that unlocking of the breechblock could take place, which would be particularly dangerous if it occurred while the firing of the shot is being delayed for some reasons (hang fire).

It was already suggested, in my Patent No. 2,361,985, of November 7, 1944, to constitute such safety means by providing in the sliding system at least one housing in which was disposed a sliding mass capable of assuming, when the system, at the end of its frontward stroke, came to strike the breech casing, a displacement at the end of which it struck the front end of its housing with a shock tending to oppose rebounding of the sliding system.

According to this prior solution, the sliding system was constituted by two slide bars interposed between the breech block and the breech casing, each sliding bar containing a sliding mass wholly enclosed in a housing open laterally both on the side of the breech casing and on that of the breechblock. Furthermore, said sliding mass was subjected to the action of imperative guiding means (in this case a plunger piston) carried by thecorresponding slide bar.

For practical purposes, the sliding mass was guided exclusively by this plunger piston and there remained, be tween said mass and the breech casing on the one hand and between said mass and the breechblock on the other hand, functional plays making it possible for the mass to slide freely in its housing. In particular, possible transverse reactions exerted on the slide bars in the course of the frontward movement of the breechblock remained without influence upon the behaviour of the sliding masses which remained normally applied against the rear end of their housing under the only actions of their return springs and inertia forces.

It is highly desirable to cause the sliding masses to remain in this rear position as long as the slide bars have not reached the end of their frontward stroke, since in this way the frontward relative movement of said masses is then of maximum amplitude (the intensity of the com- 2,788,715 Patented Apr. 16, 1957 pensating shock varying together with the amplitude of this movement).

The chief object of the present invention is to create supplementary safety means for achieving a correct positioning of the sliding mass when its frontward displacement is to start relatively to the sliding system, which safety means may be of capital importance if the sliding mass return spring fails to work (accidental breaking or weakening of said return spring).

According to the present invention, the sliding mass and the arm breech casing are made to cooperate frictionally so as to develop substantial friction forces, advantageously by contact between the adjacent walls of these two elements, and at least during the end portion of the frontward movement of the sliding system, whereby the friction forces brought into play during this phase of the operation contribute in keeping the sliding mass in its rearmost position.

A preferred embodiment of the invention will be hereinafter described with reference to the accompanying drawings, given merely by way of example and in which:

Fig. 1 shows, in elevation and with parts cut away, the breech mechanism of an automatic firearm made according to the invention.

Fig. 2 is a cross section on the line 11-11 of Fig. 1.

Fig. 3 is a plan view of a locking control member included in said breech mechanism.

The firearm includes a tube 1 provided at the rear with a breech casing 2 in which can slide, in a direction parallel to the firing axis, a movable breechblock 3 subjected to the action of a recuperator spring 4 which urges it constantly toward the front and provided with locking member 5 adapted to bear against a surface 5;: carried by the breech casing so as to hold the breechblock in its front position when a shot is being fired.

In order temporarily to keep locking member 5 in active position, I provide a sliding system constituted by two slide bars 6 disposed on either side of breechblock 3, between said breechblock and breech casing 2, and connected together by a striker holder 7 against which bears recuperator spring 4 and which extends through an elongated passage 8 provided in the breechblock, whereby the sliding system can have, once said breechblock has reached the end of its frontward stroke, a supplementary displacement which brings holding portions of slide bars 6 on locking member 5 to keep it applied against surface 50.

Rearward movement of slide bars 6 after a shot has been fired is achieved by a gas tap control system the driving portion of which is shown on the drawing and which acts upon said slide bars through a fork 9 and released accidentally.

push-piece 10.

With such a construction, slide bars 6 mightrebound toward the rear, at the end of their frontward strokes, and thus make it possible for the breechblock 3 to be In order to reduce these risks, I provide the sliding system, and preferably every slide bar 6, with at least one sliding mass or weight 11 capable of moving, in a direction parallel to the movement of the slide bars and against the action of a return spring 12, from a rearmost p0sition (in which it is applied against a rear abutment 13 rigid with the slide bar) to a front position (in which it strikes a front abutment 14 also rigid with the slide bar).

During the frontward movement of slide bars 6, weights 11 are normally kept in rear position by the combined actions of their inertia and return springs 12. When the front edge 6a of said slide bars strikes the rear edge of the firearm barrel 1, weights 11, driven by their inertia, keep moving froutwardly and strike the front ab-utments 14 of 'the'slide bars 6, thus preventing said bars from rebounding accidentally.

This compensating shock of course has a maximum intensity, and therefore a maximum efficiency, if the weights have truly started from their *rearmost positions, where they tend to be kept, as long as slide bars 6 are moving frontwardly, by the combined actions of their inertia and of return springs 12.

The object of the present invention is to reinforce this combined action and to remedy any possible breakdown of springs 12.

For this purpose, sliding weights '11 and breech casing 2 are caused to cooperate frictionally so as to develop substantial friction forces at least during the end of the frontward movement of slide bars 6.

These frictional forces will tend to keep weights 11 in their rearmost position and possibly to return them to this position if they had accidentally departed therefrom.

Friction may be developed between the system of weights 1'1 and the breech casing by rubbing elements such as elastic plates carried by one and sliding against the other.

However, preferably, the desired frictional effect is obtained by placing in direct contact with each other the adjacent faces of breech casing 2 on the one hand, and sliding weights 11 on the other hand.

In order to reinforce the pressure of application of the areas in contact, each weight may be divided over at least a portion of its length, into two portions between which elastic means are interposed to urge said portions away from each other and therefore press one of them against the breech casing.

However, it seems preferable, and anyway simpler, to make weights 11 of a single piece and to mount them on slide bars 6 in such manner that, when a slide bar tends to move toward the adjacent wall of the breech casing, the corresponding weig'htis wedged between said slide bar and said casing and therefore applied against the casing wall which tends by friction to keep the Weight in rearmost position. This wedging action is caused by the supplementary displacement of slide bars 6 engaging locking member 5 referred to hereinbefore.

According to the embodiment illustrated by the drawing, each weight 11 is constituted by a piece of general parallellepipedic shape, of lower mass than slide bar 6 but of slightly larger width, and is housed in a notch 6b provided for this purpose in the upper edge of said slide bar 6.

Weight 11 is preferably made of a height equal to the depth of this notch whereby, in the notched portion of the slide bar (which portion extends for instance from front abutment 14 to the rear of said slide bar) the weight bears against breech casing 2 both through its external side face 11a and through its upper face 11b.

Means are provided for reciprocally guiding weight 11 and slide bar 6, which means may be constituted by a sliding mortise and tenon assembly as clearly shown by Fig. 2.

Advantageously, the rear abutment 13 is given a downward and rearward inclination, whereby the combined 4 action of spring 12 and said abutment 13 keeps weight 11 applied against slide 'b'arfi when said bar -is extracted from the firearm.

It should be pointed out that friction between the sliding weights and the breech-casing according to the invention may be limited, if so desired, to certain zones of the path of travel of the weights where this effect is most important, in particular to the zone corresponding to the end of the fron'tward stroke of the slide bars.

It will sufiice for this purpose locally to arrange the guiding faces of the breach casing. so that contact between the friction cooperating parts ceases in the other zones, which is advantageous, in particular, for the zone corresponding to the frontward movement of the masses alone, which movement should not be braked.

In a general manner, while I have, in the above description, disclosed what I deem to be practical and efficient embodiments of my invention, it should be well understood that I do not Wish to be limited thereto as there might be changes made in the arrangement, disposition and form of the parts Without departing from the principle of the present invention as comprehended within the scope of the accompanying claim.

What I claim is:

An automatic loading firearm which comprises, in combination, a breech casing having a longitudinal wall and a notched part opposite said wall, a breech block slidable longitudinally in said breech casing, a locking member connected to said breech block for longitudinal movement therewith, said locking member being movable away from said breech block to engage said notched part to lock said breech block in the front limit position thereof with respect to the breech casing, at least one slide bar having a portion thereof located between said locking member and said longitudinal wall, means mounting said slide bar on said breech block for longitudinal movement thereof with respect to the breech block, said means permitting transverse movement of said portion of the slide bar with respect to the breech block, at least one sliding weight directly interposed between the longitudinal wall and the slide bar, guide means mounting the sliding weight on the slide bar for longitudinal movement with respect thereto, a rearward abutment on the 'slide bar adapted to cooperate with the weight when the latter is moved -front Wardly with respect to said slide bar, the contacting surfaces of the slide bar and locking member forming camming means causing transverse movement of the locking member toward the notched part and of the slide bar and the sliding weight toward the longitudinal wall of the breech casing, said transverse movement causing frictional engagement of the sliding weight with the longitudinal wall to maintain said sliding weight in the rear most position thereof on the breech block until the locking member is disposed within the notched part.

References Cited in the file of this patent UNITED STATES PATENTS 2,361,985 Birkigt Nov. 7, 19'44

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