FR2466740A1 - Automatic fire-arm with moving barrel - taps off gas to reduce shock load and lock firing chamber - Google Patents

Abstract

The firearm has a barrel movable in relation to the casing, and a movable weight whose rear face forms the front wall of a variable-volume chamber. Gases tapped off propel the weight forward on firing, while force on the rear chamber wall locks the firing chamber to the breech during a first stage. In a second stage, the weight strikes a lug fixed to the barrel, opening the firing chamber to operate the fiream automatically. A second quantity of gas is tapped off to between the front face of the wieght and the lug, the space between them forming a second variable-volume chamber, reducing the speed of movement and avoiding damage due to striking the lug.

Description

The present invention relates to improvements to a weapon system proposed by the same applicant in a French patent application No. 76 09102 of March 23, 1976.

 It will be recalled that the weapon system which was the subject of the above-mentioned request is of the type with fixed breech, that is to say of the kind in which the breech is integral with the carcass, or barrel of the weapon. It is necessary to underline the difference which exists between the weapons with fixed breech and the weapons with mobile breech; in these latter the breech, that is to say the part against which the cartridge case or shell socket bears at the start of the shot is a massive piece which by its inertia temporarily obstructs the recoil of the socket in the shooting chamber. An example of a mobile breech weapon of the prior art, fairly close in structure to certain embodiments of the invention, will be given below in order to better bring out the original characteristics of the weapon system of the invention.

 It is also recalled that the weapon system described in the above-mentioned patent application comprises a barrel movable relative to the carcass and a movable mass, the rear face of which constitutes a front wall of a chamber with variable volume; at the start of the blow, the mobile mass is propelled forward by borrowing gases while the rear wall of the variable-volume chamber undergoes gas thrust to first block the firing chamber against the breech; in a second step the mass strikes a front stop secured to the barrel to cause the opening of the firing chamber and allow the automatic operation of the weapon.

Tests have shown that the impact of the moving mass against the front stop was, for certain types of cartridges or calibers, so violent that it ultimately led to risks of deterioration of the weapon.

The purpose of the present improvements is to remedy this drawback by proposing an arrangement which makes it possible to absorb the shocks of the movable mass against the stop without significantly reducing the rate of fire of the weapon.

 According to the present invention, a weapon system covered by the aforementioned patent application, and succinctly defined above, is mainly characterized by a second gas borrowing carried out between a front face of said moving mass and said stop, the space located between said front face and said stop being that of a second chamber with variable volume, it follows that the pressure created in the second chamber by the second gas flow reduces the speed of the moving mass so that the weapon does not is not damaged by the impact of the latter against the stop.

 The judicious choice of the sections of the first and second chambers as well as the distance at which the second loan is made from the shooting chamber, makes it possible to adapt the kinetics of the mobile mass to the optimal functioning of the weapon.

 The second gas borrowing is carried out by means of a vent putting the barrel train into communication with the second variable volume chamber.

 It is also recalled that the weapon system described in the preceding patent application referred to above was illustrated by three alternative embodiments; in the first of these variants, the mobile mass and the variable-volume chamber which contains it, are offset from the axis of the barrel; this embodiment was given mainly to better illustrate the present invention.

 In the second and third variants the variable volume chambers and the moving masses are coaxial with the core of the barrel; more particularly in the second, the moving mass is an annular part which can slide along the barrel, the barrel being integral with the firing chamber. In the third variant, which appeared to be the one of most interest, the movable mass consists of the barrel itself, the rear part of which can slide in a so-called rear part, shaped as a sleeve, incorporating the shooting chamber. The present improvements apply equally well to any one of these three variants as well as to all the other embodiments which could be imagined on the basis of the principles set out in the above-mentioned patent application.

 The present invention also proposes to conform the "coaxial sliding parts", in particular of the third embodiment, into a "drawer", so as to provide an additional parameter for controlling the kinetics of these parts.

The improvements in accordance with the present invention will be better understood from the description which will be given of the variant embodiments comprising them, in relation to the figures of the appended plates in which
Fig. 1 is an illustration of a weapon system with a movable breech from the front, given by way of illustration of the differences between this weapon system and that to which the present invention relates,
Fig.2 is a partial schematic section of a weapon according to the first aforementioned variant and comprising the improvements of the present invention,
Fig.3 is similarly the section of a weapon according to the third variant mentioned above,
Fig.4 is an illustration of the operation of the weapon of the previous figure when the shot starts,
Fig. 5 is a similar illustration at a later stage,
Fig. 6 is an illustration similar to another later stage,
Fig. 7 is an illustration similar to a fourth stage comprising the opening of the firing chamber,
FIG. 8 is an illustration of the operation of a weapon comprising the improvements of the present invention in which sliding parts operate on a drawer principle, these parts being taken a few moments after the start of the shot, and
Fig. 9 is an illustration of the operation of the same weapon at a later stage.

In fig.l a weapon of the pistol-submachine type essentially comprises a carcass 1, a barrel 2 movable relative to the carcass and a breech 3, the latter two elements being movable relative to the carcass and one relative to the other, a variable volume chamber 3 is between the barrel and the carcass; a vent 4 puts the chamber 3 in communication with the core 5 of the barrel just in front of the socket 6 of the cartridge. At the start of the shot, thanks to the gas pressure developed in chamber 3 the barrel accompanies in its rearward movement the movable breech and the opening of the
chamber of shooting is thus delayed.

Such a weapon system which has its own advantages and disadvantages, is said to have a movable breech and differs radically in its operation from the
weapon system to which the inventive weapon system is attached
tion.

In fig. 2 a weapon of the invention, con
form a first variant of the above request
tee of the same Applicant, essentially comprises a carcass 10
forming a breech, a barrel 11 and a chamber 12 in which a moving mass 13 can move. A vent 14 connects
the core of the barrel and the rear end of chamber 12 behind
the moving mass 13; the vent 14 is located in front of the firing chamber 15 just in front of the socket 16 of a cartridge. At the start of the blow, the gas pressure is communicated in the variable volume chamber at the rear of the moving mass 13 ; the pressure developed in the. variable volume chamber 12 has the effect of pressing the rear face of the barrel against the breech and of throwing the movable mass 13 forward until it meets a stop 17 secured to the barrel.

According to the present improvements, the space 18 located between the front face of the movable mass 13 and the stop 17 constitutes a second chamber with variable volume, and this
second variable volume chamber 18 communicates with the core 19 of the barrel by a second vent 20. When after the start of the shot the projectile has exceeded the vent 20, a portion of the gases is borrowed from the core of the barrel to come create in the chamber 18 a back pressure opposing the movement of the moving mass i3; it follows that the movement of the latter is slowed down.

In fig. 3 a weapon conforming to the three
sth variant of the aforementioned patent application, has an operating principle completely analogous to that of the weapon of the
previous figure; however, it differs in structure.

Thus the moving mass is constituted by the barrel 21; the latter slides in a rear part 22 incorporating the firing chamber 23.

 A first variable volume chamber is delimited by front and rear walls formed respectively by the rear edge 24 of the barrel and the bottom 25 of the cylindrical housing of the rear part in which the rear end of the barrel slides. According to this arrangement, the socket opens directly into this variable-volume chamber and this direct outlet takes the place of the first vent 14 of the previous figure.

 A second variable volume chamber 28 is provided with front and rear walls defined respectively by a front stop 26 of the rear part 22, and by a shoulder 27 of the barrel. It is clear that, as in the previous case, the two rooms have volumes varying inversely from one another. A second vent 29 opens into the second chamber 28, this second vent being located at a certain distance in front of the firing chamber and opening out in front of the shoulder 27 of the barrel.

Note that compared to the example in fig.l the role of this vent is not to allow a borrowing of gas to cause the recoil of the barrel, but to allow a borrowing of gas to slow the movement of a mass mobile which, in this case, happens to be the barrel itself.

 On fig.4 to 7 the operation of a weapon of the previous figure is as follows: at the start of the shot (fig.4) a pressure is instantly developed in the first variable volume chamber 30; this pressure presses the rear part comprising the firing chamber, against the breech 31, while the barrel 21 initiates a forward movement; it will be noted that the forward movement of the barrel is very slow compared to the movement of the projectile 35, having regard to the respective mass of one and the other.

The speed of movement of the barrel increases while the movement of the Drojectile continues in the barrel (fig. 5).

 At a certain stage (fig.6) the projectile 35 has exceeded the vent 29 and the pressure is established in the second variable volume chamber 28; consequently the pressure of the gases in the chamber 30 is compensated at least in part by the pressure of the gases in the chamber 28.

At a later stage, not shown in the figures, the projectile left the barrel and the pressure in the chamber 30 dropped suddenly while the pressure in the chamber 28 is maintained longer due to the small cross section of the vent, which has the effect of decelerating the advance movement of the barrel.

 When (fig.7) the shoulder 27 of the barrel meets the stop 26, the barrel has just the energy necessary to drive the rear part 22 forward and open the firing chamber 23 to eject the casing and reload the weapon with new ammunition.

 In FIGS. 8 and 9, a weapon belonging to the same variant as that of FIGS. 3 to 7 differs therefrom however by certain peculiarities of its structure.

In this variant, the barrel 46 is always provided with a cylindrical shoulder 41, but the vent 42 instead of opening, as in the previous case at the front of this shoulder, opens along the cylindrical surface of the shoulder. .

The rear part 47 comprising the firing chamber 48 is always shaped as a sleeve for slidingly housing the barrel and its shoulder, but unlike the weapon of the preceding figures, the inside diameter of the sleeve, at the front of the range 43 in which the shoulder 41 slides, widens into a recess 44 intended to allow the vent 42 to open into the second variable-volume chamber 45, when the barrel has moved some distance forward in the sleeve (case of Figure 9).

This arrangement giving the barrel and the rear part the role of a slide distributor results in making the introduction of gases into the second chamber subordinate, no longer to the position of the projectile in the barrel as in the previous case, but to the position of the barrel along the rear part in which it slides; the introduction of an additional parameter, namely the position of the barrel in the rear part comprising the firing chamber, makes it possible to better control the kinetics of the abovementioned parts, namely the rear part 47 and the barrel 46, it being understood that it is possible to choose, within certain limits, the position of the vent along the core of the barrel as well as the lengths of the recess 44 and / or of the shoulder 41.

It will also be noted that, depending on the specific needs, the vent 42 could have its ends offset with respect to each other along the axis of the barrel, this can be obtained, either by giving the vent a path oblique, either by giving it a broken path.

 Although particular embodiments have been given by way of illustration of the possibilities of carrying out the improvements in accordance with the invention, it should be understood that these extend to any weapon system as defined by the claims which follow .

Claims (2)

1.- Weapon system comprising a barrel movable relative to the  carcass and a moving mass, the rear face of which constitutes  a front wall of a variable volume chamber; the mass mobile being at the start of the stroke propelled forward by  borrow gas while the back wall of the chamber  variable volume undergoes gas thrust to perform in  firstly, the blocking of the firing chamber against the cylinder head ; the mass then coming to strike a front stop secured to the barrel to cause the opening of  the firing chamber and allow automatic operation  weapon, characterized by a second gas loan made in be a front face of said movable mass and said stop,  the space between said front face and said stop being that of a second variable volume chamber,  where it follows that the pressure created  in the second room by the second reduced gas loan the speed of the mobile so that the weapon is not damaged by the impact of the latter against the stop 2.-weapon system according to claim 1, characterized  in that the second gas loan is  realized by means of a vent, said second, bringing into communi cation the core of the barrel with the second volume chamber varia  corn ;  3. A weapon system according to claim 2, wherein the mass  mobile is constituted by the barrel itself, the part of which  rear can slide in a piece called rear conform  sleeve incorporating the firing chamber, characterized in that the second vent opens into the second variable volume chamber at the front of a shoulder  cannon ment; 4.- weapon system according to claim 2, characterized - in that the inside diameter of the sleeve widens in one  obviously, and - in that the vent opens along the cylindrical seat from the shoulder, from which it follows that the vent may lead  expensive in the second variable volume room when the  barrel moved a certain distance forward in the sleeve, this arrangement giving the barrel and the part  the role of a drawer dispenser.