US3845689A - Breech-block for automatic guns, more particularly automatic shotguns - Google Patents

Abstract

The breech-block for an automatic gun of the type having a pivoted lock which is adapted to engage in a cavity provided in the top of the receiver of the gun is further provided with a spring biased cylinder arranged to engage a notch in the pivoted lock to maintain the pivoted lock in a retracted position during the return movement of the breech-block until the pivoted lock is positioned to re-enter the cavity in the receiver.

Description

United States Patent [191 Zanoni 1 Nov. 5, 1974 BREECH-BLOCK FOR AUTOMATIC GUNS, MORE PARTICULARLY AUTOMATIC SHOTGUNS [75] Inventor: Ernesto Zanoni, Brescia, Italy [73] Assignee: S.p.A. Luigi Franchi, Brescia, ltaly [22] Filed: May 21, 1973 [21] Appl. No.2 362,125

[30] Foreign Application Priority Data May 19, 1972 Italy 024572/70 [52] US. Cl. 89/181, 89/190 [51] Int. Cl. F41d 3/00 [58] Field of Search 89/164, 168, 176, 181, 89/ 190 [56] References Cited UNITED STATES PATENTS 2,418,946 4/1947 Loomis 89/164 Primary Examiner-Stephen C. Bentley Attorney, Agent, or Firm-Sughrue. Rothwell, Mion. Zinn & MacPeak [57] ABSTRACT The breech-block for an automatic gun of the type having a pivoted lock which is adapted to engage in a cavity provided in the top of the receiver of the gun is further provided with a spring biased cylinder arranged to engage a notch in the pivoted lock to maintain the pivoted lock in a retracted position during the return movement of the breech-block until the pivoted lock is positioned to re-enter the cavity in the receiver.

1 Claim, 6 Drawing Figures PATENTEUNUY 51974 sum 20? 3 3'845'689 Pie. 13

BREECH-BLOCK FOR AUTOMATICGUNS, MORE PARTICULARLY AUTOMATIC SHOTGUNS BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a breech-block for automatic guns, more particularly shotguns.

2. Prior Art The breech-blocks currently used in automatic shotguns comprise a substantially parallelepipedic body with the main axis disposed in alignment with the barrel of the gun, a carriage supporting the body and provided with reciprocating rectilinear movement in the direction of the axis of the barrel. For this movement, the carriage is in engagement with the shafts or rods controlled by a recoil mass normally provided in an automatic gun and activated by a shot gas recovery device.

The parallelepipedic body is crossed in one of its central portions by a continuous hole generally having a rectangular profile, the longer side of which constitutes the seating for a pivoted lock, the stem of which engages in an oscillating manner in an eccentrically disposed seating in the front base of body, and the suitably shaped head of which is positioned close to the rear base of this body.

Projections or cams rise up in the continuous hole from the carriage with which they form a single piece. These projections or cams are provided at the rear with contours paired with the contour of the lower portion of the pivoted lock, with which they are intended to engage in a detachable manner. This pivoted lock is provided at the upper part of its head with a projection designed to engage in a corresponding cavity provided in the top of the gun stock in which the breech-block is displaced.

The parallepipedic body and the carriage beneath it are slidably engaged; the sliding distance being limited to a stretch defined by the course which the projections or cams can travel within the continuous hole. More precisely, this course is limited in front by the meeting of the projections or cams and the from base of the body, and at the rear, by the engagement of the projections or cams with the lower contour of the head of the pivoted lock.

The breech-block of the type described above operates as follows: After a shot has been fired, the rods draw the carriage backwards. After a short initial course, the carriage brings the cams into engagement with the lower contour of the head of the pivoted lock. The contour and engagement are such that the pivoted lock frees itself from the cavity provided in the top of the receiver in which the breech-block is displaced. After the release of the pivoted lock, the carriage and the rectangular body together continue the course towards the back of the receiver. At the end of this course, the spring means, which have already been described, move the rods forward, and with them the breech-block. On taking up its initial position, the front base of this parallelepipedic body abuts against the bottom of the new cartridge positioned in the shot chamber, and is arrested there, while the carriage advances a further limited stretch until the two cams rest against the front base of the body. With this further limited advancement of the carriage, the cams and the pivoted lock are disengaged and the pivoted lock is pushed upwards where it comes into engagement with the abovementioned cavity provided in the top of the receiver. This engagement permits the closing of the breechblock and another shot can then be fired.

In as far as the above-described breech-blocks are concerned, however widely they are used and however advantageous they may be from various standpoints, they still have serious disadvantages. Their most common disadvantage is that the pivoted lock, after being released from the cavity provided in the top of the receiver in which the breech-block is displaced, is engaged in an essentially loose manner by the lower cams of the carriage. By reason of this engagement and owing to the fact that the pivoted lock can oscillate about the end of its stem during the passage of the breech-block to the rear of the receiver and during its return to its initial position, a hammering effect on the part of the head against the top of the receiver, is produced. This hammering fairly rapidly causes the formation of indentations or other similar changes to the surface of the receiver. To obviate such disadvantages, the top of the receiver in which the breech-block is displaced, may be protected by an element which may be easily replaced after the gun has been used for a certain period of time. However, this leads to the hardening of a strip or track in the top of the receiver which the pivoted lock of the breech block strikes.

SUMMARY OF THE INVENTION The main object of the invention is to provide a breech-block of the type described above, intended for automatic guns, more particularly shotguns, having structural and operational features capable of overcoming the above-mentioned disadvantages. These features should be such that during the passage of the breech-block the pivoted lock is prevented from hammering in any way on the top of the receiver. They should not require the use of devices which are delicate or difficult to produce, or which are delicate in operation or require complicated preliminary adjustment of the gun to which the breech-block is being applied.

Another object of the invention is that of providing a breech-block of the type mentioned above, which is relatively simple to produce using materials and devices commonly found on the market, thereby also rendering it profitable from a strictly economical stand point.

These and other objects, which will be rendered more apparent in the following description are achieved by a breech-block for automatic guns, more particularly automatic shotguns, according to the invention. This breech-block comprises a substantially parallelepipedic body, the longer axis of which is aligned with the axis of the barrel of the gun, a seating in this body, a pivoted lock mounted so as to oscillate in this seating about one of its ends, a carriage for the support of this body and the displacement of the breech-block, cam means integral with the carriage and detachably connected to the pivoted lock in its seating, intended for the engagement and'disengagement ofthe plunger in andfrom the cavity provided in the top of the receiver of the gun in which the breech-block is displaced. This breech-block is characterized in that it comprises an element which engages with this pivoted lock after the release of the latter from the cavityby way of the cam means and by way of meansfor disengaging the element from the pivoted lock before it-reengages in the cavity provided in the top of the receiver.

Other objects, features and advantages of the present invention will be made apparent from the following detailed description of a preferred but not exclusive embodiment of a breech-block according to the invention provided by way of a non-limitative example with reference to the accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a breech-block according to the invention,

FIG. 2 shows the same breech-block as represented in FIG. 1 but with the parts separated,

FIGS. 3 and 4 are sectional views of the breech-block according to the invention in the end positions of its course within the receiver of an automatic gun,

FIG. 5 is a sectional view from above of the breechblock shown in the preceding figures, in a closing" position,

FIG. 6 shows a section along the line Vl-VI of FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENTS With reference to the above figures, the breechblock according to the present invention, designated generally by 1, is particularly suitable for automatic shotguns. This breech-block comprises an essentially parallelepipedic body 2 provided in the receiver 3 (in which the breech-block is displaced), with its longer axis in alignment with the axis of the barrel 4 of the gun, a carriage 5 for the support of the body 2 and for the displacement of the breech-block. For this displacement, the carriage is in engagement with the shafts or rods 6 and 7 controlled by recoil means (not shown) in turn activated by a shot gas recovery device (not represented). This parallelepipedic body 2 is provided, in one of its central portions, with a rectangular, continuous hole 8 disposed with its longer side parallel to the main axis of the body 2. This continuous hole 8 constitutes the seating for receiving the pivoted lock 9, the end 10 of which is mounted for oscillation in a seating 11 eccentrically provided in the front base of the body 2 of the breech-block. At the opposite end to the oscillating end 10, this pivoted lock is provided laterally with projections 12 and 13 expanding at the lower part and having identically shaped contours. Projections or cams l4 and 15 rise up in the continuous hole 8 from the carriage 5, with which they form a single piece. At the rear, these projections have contours l6 and 17 paired with the front contours 12a and 13a of the projections 12 and 13 respectively, of the pivoted lock. These projections 12 and 13 are provided at the rear with an inclined profile designed to engage in a known way, which will subsequently be described in more detail, with the inclined face 18 defined by a block 19 provided on the back of the carriage 5. At the opposite end to the oscillating end 10, the pivoted lock 9 is provided with a shaped projection 20 designed to engage with the cavity 21 provided in the top of the receiver 3, in which the breech-block l is displaced.

The body 2 is provided on its side 22 turned towards the ejector 23, normally provided in automatic guns to eject the spent cartridge, with a longitudinal groove 24 defining at the rear a seating 24a in which a spring engagement member, generally designated by 25, is slidably arranged. This member 25 consists of a small hollow cylinder 26 having a blind base. A spring 27 is arranged in this cavity. This spring 27 is guided and supported by a stem or rod 28, which, in turn is located in a plate 29. This plate 29 is connected at the rear to the body 2 and is centrally provided with a continuous hole 30, the diameter of which is such as to permit the passage of the control shaft of the precussion pin (not shown). To locate the element 25 in the structure described above, the cylinder 26 is connected at the rear to the body 2 in an eccentric position, i.e., in a position displaced towards the side 22 of the body 2. The cylinder 26 has a smooth lateral zone 31 intended to be aligned with the base 24b of the groove 24, in such a way as not to interfere with the previously mentioned ejector 23 during the movement of the breech-block within the receiver 3. At the rear end of this fiat zone 31, the cylinder 26 is provided with a projection 32 dimensioned so as to interfere with the ejector 23. On its projection 12 which expands towards the bottom, the plunger 9 is provided with a notch 33, the structure and depth of which are such that it engages, in a manner which will be described subsequently, with the shaped head 34 of the cylinder 26.

The breech-block according to the present invention operates as follows: When a shot is ready to be fired, the breech-block l is in the position shown in FIG. 3. In this position, the cams 14 and 15 of the carriage 5 are disengaged from the front contours of the projections 12 and 13 of the pivoted lock 9. The pivoted lock 9 is in a raised position with the upper projection 20 in engagement with the cavity 21 provided in the top of the receiver 3, in which the breech-block 1 is displaced. The projection 32 of the cylinder 26 rests against the ejector 23 and the cylinder 26 is in its most retracted position in the seating 24a defined at the rear of the groove 24 of the body 2. In this position, the spring 27 within the cylinder 26 is compressed between the blind base of the cylinder 26 and the annular collar 35 provided at the rear of the stem 28 to support and guide this spring. When the shot has been fired, the rods 6 and 7 draw the carriage 5 backwards. After a short course, the carriage 5 brings the cams 14 and 15 into engagement with the front contours of the projections 12 and 13 of the pivoted lock 9. This engagement simultaneously gives rise to the lowering of the pivoted lock 9 and the freeing of its upper projection 20 from the cavity 21 and the joining of the carriage 5 with the body 2 of the breech-block. From this moment onwards the entire breech-block is displaced, being pushed by the rods 6 and 7 towards the back of the gun. In correspondence with this displacement, the projection 32 of the cylinder 26 is removed from the ejector 23, as a result of which, the spring 27, which is no longer compressed, moves the cylinder 26 forwards. The cylinder 26 then engages in a releasable manner in the notch 33 of the lowered pivoted lock 9. This engagement lasts throughout the entire backward course of the breech-block l and throughout the return course of the same. As a result, the pivoted lock 9 remains rigidly locked in its lowered position during the outgoing and return courses of the breech-block. During the out going course, the breech-block l compresses by way of the rod 36, which is connected thereto in a known way, a spring (not shown) which is responsible for the return movement of the breech-block.

Towards the end of the outgoing course of the breech-block, (H0. 4), a conveyor 37, which is moved in a known way, charges the shot chamber with the new cartridge. Towards the end of the return course, there occurs first the reengagement of the projection 32 of the cylinder 26 and the ejector 23. With regard to the body 2, this reengagement gives rise to the retraction of the cylinder 26 with the renewed compression of the spring 27. With this retraction, the cylinder 26 disengages from the notch 33. Immediately after this disengagement, the body 2 readopts the position indicated in H6. 3, while the carriage 5 continues to advance for a short distance during which the cams l4 and move away from the front contours of the projections 12 and 13 of the pivoted lock 9 and the latter is raised from the inclined side 18 of the block 19 provided at the back of the carriage, so that the upper projection 20 is reinserted in the cavity 21 in the top of the receiver 3. The gun is now ready to be fired once again.

It is obvious from what has been described and illustrated that the breech-block according to the present invention completely fulfils all the aims in view, with particular reference to the blocking efficiency of the pivoted lock 9 in the lowered position during the course of the breech-block towards the back of the gun and during its return movement, to the structural simplicity of the preferred blocking means, and, not least, the economical production and application of these means in a breech-block for automatic guns.

What is claimed is:

l. A breech-block for automatic guns, more particularly for automatic shotguns, comprising a substantially rectangular body disposed with the larger axis in alignment with the axis of the barrel of the gun, a seating in said body, a pivoted lock mounted in an oscillating manner about one of its ends in said seating, a carriage for supporting said body and displacing the breechblock, cam means integral with the carriage and removably connected to the pivoted lock in said seating, intended for engagement and disengagement of the pivoted lock in and from a cavity provided in the top of the receiver of the gun in which said breech-block is displaced, said breech-block being characterized in that it comprises a member which engages with the pivoted lock after its release from the cavity by way of said cam means, and means for disengaging said member from the pivoted lock before it reengages in the cavity provided in the top of the receiver, said means for disengaging said member from the pivoted lock comprises a raised part laterally defined by the hollow cylinder and projecting outside the groove and the side of the body facing towards the ejector, said projecting part interfering with the ejector during the return course of the breech-block and determining, in contrast to the spring means, the disengagement of the cylinder from the notch of the pivoted lock.

Claims (1)

1. A breech-block for automatic guns, more particularly for automatic shotgUns, comprising a substantially rectangular body disposed with the larger axis in alignment with the axis of the barrel of the gun, a seating in said body, a pivoted lock mounted in an oscillating manner about one of its ends in said seating, a carriage for supporting said body and displacing the breechblock, cam means integral with the carriage and removably connected to the pivoted lock in said seating, intended for engagement and disengagement of the pivoted lock in and from a cavity provided in the top of the receiver of the gun in which said breech-block is displaced, said breech-block being characterized in that it comprises a member which engages with the pivoted lock after its release from the cavity by way of said cam means, and means for disengaging said member from the pivoted lock before it reengages in the cavity provided in the top of the receiver, said means for disengaging said member from the pivoted lock comprises a raised part laterally defined by the hollow cylinder and projecting outside the groove and the side of the body facing towards the ejector, said projecting part interfering with the ejector during the return course of the breech-block and determining, in contrast to the spring means, the disengagement of the cylinder from the notch of the pivoted lock.

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