Direct interlocking device for the breech block and the firing pin of automatic firearms

Sept. 5, 1933. ascottietal 1,925,776

DIRECT INTERLOCKING DEVICE FOR THE BREECH BLOCK AND THE FIRING PIN OF AUTOMATIC FIREARMS

Filed Feb. 24, 1932

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Inventors;

Alfredo *Scolli Giov&nni Jia ii isiaAnelo Hi £>orlolo Giuseppe C&zngi

Atlomey:

Patented Sept. 5, 1933

1,925,776

UNITED STATES PATENT OFFICE

1,925,776

DIRECT INTERLOCKING DEVICE FOR TUB BREECH BLOCK AND THE FIRING PIN OF AUTOMATIC FIREARMS

Alfredo Scotti, Giovanni Battista Anelotti, and Bortolo Giuseppe Campi, Brescia, Italy

Application February 24, 1932, Serial No. 594,884, and in Italy February 24, 1931

Claims.

The invention has for its object an arrangement applicable to automatic firearms in which are provided means adapted to prevent the firing pin from detonating the cartridge before the 5 breech block reaches the position where the breech is completely closed and the breech block from receding before the gas pressure produced by the explosion is sufficiently reduced. This arrangement is applicable to all kinds of auto10 matic firearms in which the breech block recoils under the action of the explosion gases and returns to the closed position under the action of a restoring spring; the firearm may moreover be of any type: pistol, rifle, machine gun or heavy 15 gun.

Firearms are already known in which there are provided parts adapted to retain the firing pin until the moment when the breech block has reached the position where the breech is com20 pletely closed and in many cases these parts are controlled by the breech block, which moves forwardly and rearwardly and rotates at the ends of the reciprocating movements in co-operation with other parts arranged in the -breech of the 25 firearm.

Firearms are also known in which there are provided locking members controlled by the successive movements of the barrel, by a gas piston or by similar means which hold the breech block ³⁰ in the closed position until the gas pressure resulting from the explosion is sufficiently reduced.

In all these known arrangements additional members are necessary; these members must have as small bulk as possible and are conse³⁸ quently of light construction, although they are subjected to continuous and powerful hammering, this leads to the risk of frequent derangement and fracture which is very undesirable and dangerous in firearms..

⁴³ According to the present invention these undesirable features are eliminated by an arrangp.ment in which the breech block itself houses the firing pin which is pressed forward positively by the restoring spring without the necessity for the ⁴⁵ trigger spring usually employed for the actuation of the firing pin; the said breech block, after reaching the position where the breech is closed, ceases to restrain the firing pin which, in its turn, advances and positively effects, the ° locking of the breech block in the closed position and retains it in this position until acertain member, which is displaced by the release of the explosion gases or otherwise, returns the said firing pin into the disengaged position.

⁰⁰ in one possible constructional embodiment the (CL 42—3) breech block is provided in known manner with projections which engage in grooves formed in the breech, a small forward end portion of which has a helicoidal form so as to cause rotation of at least part of the breech block about the axis 60 of_s the firearm·; this arrangement is characterized in that the firing pin, which is positively urged by the restoring spring, is provided with shoulders which press against a flange arranged in the breech and that the said flange is provided 65 with indentations which arrive opposite the shoulders of the firing pin when the breech block effects its final closing rotation, so as to permit of the shoulders entering therein to complete the stroke of the firing pin and to effect the tangen- 70 tial locking of the breech block which cannot again move rearwardly until the firing pin is returned again by a suitable part of the guh actuated by the release of the explosion gases.

The subsequent retraction of the firing pin 75 which is necessary in order to disengage its shoulders from the indentations of the breech block to permit the latter to rotate as it recedes in its turn, may be effected by the recoil of the gun or by a gas piston or known type; for this 80 purpose it is sufficient to provide the firing pin with a projectioh formed and arranged so as to be capable of actuation by the member selected for this purpose.

In order to render more clear the essential na- 85 tore and scope of the invention, one constructional example is. illustrated in the accompanying drawing, in which:

Figs. 1 and 2 are two side views of an automatic firearm, which illustrate the same in two ⁹³positions, namely with the breech open and closed respectively.

Fig. 3 is a longitudinal section of Fig. 1.

Figs, 4, 4α, 4b show respectively a. side, view, a front view and a cross section of the firing pin ⁰⁵ . provided with the shoulders and the engaging tooth. .

. Figs. 5, 5α and 5b are similar illustrations of the breech block.

In the. constructional example illustrated, the ³³³breech block 5 recoils under the action of the explosion gases and is returned to the closed position by a restoring spring 6. The said breech (block is provided with a longitudinal cavity, in “Which the firing pin 4 is adapted to slide and with ¹⁰⁵projections 5α which engage in grooves 5b formed in the breech of the firearm, said .grooves 5b having at their foremost end helicoidal deviations 5c. When the breech, block returns to the closed position, it is guided by its projections 5α ¹¹⁸

1,θ2δ_; which engage in the grooves 5b; at the end of its stroke it is caused to undergo a slight rotation by means of the helicoidal deviations 5c of said grooves. This known arrangement is 5 made use of to assure the operation of the arrangement according to the present invention.

The firing pin in this firearm is not provided with a special trigger spring but it is actuated positively by the restoring spring 6. The firing 10 pin has two shoulders 4α, 4b which normally abut against the edge of a flange formed in the breech: in the example shown this flange consists merely of the circular edge of the rear surface of the breech block. The shoulders 4α, 4b 15 transmit to the breech block the pressure of the restoring spring which returns it to the closed position. During this forward movement the firing pin occupies a somewhat backward position in the breech block¹ which does not permit fit to 20 reach the cartridge. But the edge of the retaining flange in the breech block is provided with indentations 5d, 5e which, owing to the final rotation of the breech block arrive opposite the shoulders 4α, 4b; under the action of the spring 25 6 the firing pin can then advance a little further in the breech block, which is in its closed position, and consequently reaches the point where it detonates the cartridge.

The engagement which is thus effected between 30 the shoulders 4α, 4b of the firing pin and the indentations 5d, 5e of the breech block prevent the latter from rotating so as to be able to recoil, so that the firing pin effectively locks the breech block in its closed position during the first pe³⁵ riod of the release of the explosion gases. This engagement always takes place very smoothly and perfectly balanced since it takes place in a tangential direction and not in an axial direction as is the case in known arrangements.

⁴⁰ In the constructional example illustrated, the unlocking of the breech block is entrusted to an ordinary gas piston 3, working in a cylinder 2 arranged at a convenient part of the barrel 1 of the firearm. This piston, before the bullet ⁴⁵ leaves the barrel, is forced rearwardly by the gases which enter the cylinder 2 and retracts the projection 4c which is- integral with the firing pin. The firing pin is then moved rearwardly and frees the breech-block which, under the ⁵⁰ action of the remaining gas pressure, recoils in turn after having executed a partial rotation in the helicoidal grooves 5c, which movement brings the unindented portion of the flange of the breech block opposite the shoulders 4α, 4b of the firing ⁶⁵ pin; under the action of the gases the breech block completes its recoil stroke carrying with it the firing pin and loading the restoring spring 6.

Naturally the projection 4c of the firing pin could be actuated by the recoil of the barrel if ⁸³ the arrangement is applied to a firearm with a recoiling barrel.

In the constructional form shown the projection 4c of the firing pin is made use of to retain _ the firearm in the cocked position and ready to ⁶⁵ be discharged, since this projection can be engaged with the projection 4d of the tumbler. This engagement keeps the return spring 6 strained and the breech block cannot complete its forward stroke until the tumbler is displaced. ⁷⁰ This arrangement adds the further advantage that the barrel of the gun contains a cartridge only at the moment of firing.

The advantages obtained by this arrangement are obvious since the number of parts is reduced ⁷⁵ to an absolute minimum, they are of simple de,779 sign and easy to manufacture and they are not liable to any; kind of derangement.

Naturally the constructional arrangement of the different parts will have to be varied in accordance with the type and the nature of the ⁸automatic firearm to which the invention is applied, but such alterations will be obvious to persons skilled in the construction of firearms.