US3538810A

US3538810A - Barrel attachment for a firearm

Info

Publication number: US3538810A
Application number: US810862*A
Authority: US
Inventors: Bernard Maillard
Original assignee: Brevets Aero Mecaniques SA
Current assignee: Brevets Aero Mecaniques SA
Priority date: 1967-07-31
Filing date: 1968-10-21
Publication date: 1970-11-10
Anticipated expiration: 1987-11-10

Description

iliiit Inventor Appl. No.

Filed Patented Assignee Priority Bernard Maillard Geneva, Switzerland 810,862

Oct. 21, 1968 Division of Ser. No. 717,524, Apr. 1, 1968, now Pat. No. 3,447,418 Nov. 10, 1970 Brevets Aero-Mecaniques S.A. Geneva, Switzerland a society of Switzerland July 31, 1967 Luxembourg BARREL ATTACHMENT FOR A FIREARM 7 Claims, 7 Drawing Figs.

ILLS. Cl 89/159, 42/75 Int. Cl F41d 1/06 Field of Search 42/75.2; 89/159: I62. I75

[56] References Cited UNITED STATES PATENTS 3,277,786 10/1966 Maillard Primary Examiner-Benjamin A. Borchelt Assistant Examiner-Stephen C. Bentley Attorney- Larson, Taylor and Hinds ABSTRACT: A firearm comprising at the interior of the breechcase a gas conducting element, a sleeve to which the barrel of the firearm is fixed by a bayonet joint, and a nut which is screwed into the front of the breech case and which serves to maintain the sleeve in the breech case. The sleeve is adapted to recoil with the barrel with respect to the breech case and is guided in recoil by the nut. The sleeve has two successive collars: a front collar of a diameter equal to the interior diameter of the nut and a rear collar of a diameter equal to the interior diameter of the breech case, which is greater than the diameter of the front collar. The rear collar is disposed behind the nut for maintaining the sleeve longitudinally with respect to the nut, and transversely with respect to the breech case. The interior diameter of the nut is sufficiently large so that the gas conducting element can pass therethrough without touching it.

Patented Nov. 10,1970

Sheet U nmofig. @N E Patented Nov. 10, 1970 I Z of 3 Sheet Patented Nov. 10, 1970 Sheet 3 of This application is a division of my previous application Ser. No. 717,524 filed Apr. 1, l968, now U.S. Pat. No. 3,447,418.

The present invention relates to firearms that are at least semiautomatic, in particular to automatic firearms of calibre advantageously comprised between and 50 mm. Firearms of these types recock themselves automatically after each round, and the firing of the following round can either require an action on the part of the gunner (semiautomatic firearms) or not (automatic firearms).

The invention comprises principally the following features, taken separately or in any combination.

According to a first feature of the invention, a firearm comprises a substantially cylindrical breech mechanism adapted to be displaced in an alternating translatory movement in a breechcase having towards the rear an interior shape and an exterior shape which are substantially rectangular, this breechcase having in one of the small sides of its substantially rectangular cross section an ejection passage for the ejection of the empty cartridge cases and in the two large sides of said cross section introduction openings for the introduction of cartridges coming respectively from two feed mechanisms which can be alternately put in firing position, a helical counterrecoil Spring being provided between the breech mechanism and the rear part of the breechcase, the firearm being characterized by the fact that the part of the breechcase which is of substantially rectangular cross section, has at the level of the cartridge introduction openings, four guiding surfaces for guiding the breech mechanism as well as for guiding the counterrecoil spring whose exterior diameter is substantially equal to the exterior diameter of the breech mechanism, said guiding surfaces being situated on a common geometrical cylinder of revolution about an axis having the same direction as the axis of the barrel of the firearm.

According to a second feature of the invention, a firearm is adapted to receive two feed mechanisms articulated on the breechcase of the firearm and controlled so that one of them is in firing position when the other is out of firing position and vice versa, each feed mechanism having a mechanism for advancing cartridges and for transmitting motion housed in the feed mechanism and a driving member adapted to be displaced in a direction substantially parallel to the axis of the barrel of the firearm, the firearm being characterized by the fact that it comprises for the two feed mechanisms a single motor member having alternating longitudinal motion connected to a recoiling part of the firearm and of form and position such that it meets, during its recoil motion, only the driving member of the feed mechanism that is in firing position.

According to a third feature of the invention, a firearm comprises in the interior of a breechcase, on the one hand, a sleeve to which the barrel of the firearm is fixed in a removable manner by a bayonet joint, and on the other hand, an annular connecting member such as a nut which is screwed on the front of the breechcase and which serves for maintaining the sleeve in longitudinal direction towards the front and in transverse direction at the same time, connecting means being provided between the part of the barrel and/or the sleeve situated at the front of the nut and a zone situated at the rear of the sleeve between the sleeve and the breechcase, more particularly, the sleeve of this firearm being adapted to recoil with the barrel with respect to the breechcase and being guided in translation by said nut, the firearm being characterized by the fact that the sleeve has two successive collars, namely a front collar whose diameter is equal to the interior diameter of the nut and which is disposed at the interior of this nut for maintaining the sleeve transversely with respect to the nut, and a rear collar whose diameter, which is greater than the diameter of the front collar, is equal to the interior diameter of the breechcase and which is disposed behindthe nut for maintaining the sleeve longitudinally with respect to the nut and transversely with respect to the breechcase, and by the fact that the interior diameter of the nut is sufficiently large so that an intermediate element of said connecting means passes through the front collar without touching the nut, due to which it is possible to unscrew or screw the nut for dismantling or reassembling the sleeve, without preliminary dismantling of the connecting means.

According to a fourth feature of the invention, a firearm has an ejection system comprising an extractor carried by the movable breech mechanism, and diametrically opposed, an ejector carried by the breechcase and comprising at the front a transverse striking surface for the rear edge of the cartridge case to be ejected, which ejector is controlled by the breech mechanism in a manner to present said striking surface in the trajectory of this rear edge during the recoil of the breech mechanism, the firearm being characterized by the fact that the ejector comprises, at the front of this striking surface, a projection adapted to strike transversely the lateral surface of the cartridge case, before the impact with the rear edge, in a manner to tip the cartridge case before this impact in the direction of the ejection passage, which attenuates the violence of said impact.

The present invention will be clearly understood from the following specific description of a preferred embodiment of the invention, given, merely by way of example, with reference to the accompanying drawings, in which:

FIGS. 1 and 2 (both divided by a vertical broken line into two parts a and I) intended to be considered end to end) show a firearm according to the present invention, respectively in vertical section and in-horizontal section along Il-ll of FIG. 1;

FIGS. 3 and 4 are sections along the lines Ill and 1 respectively of HQ 1;

And FIG. 5 illustrates the operation of the ejection system visible in FIG. 1.

The firearm shown in the drawings is a heavy machine gun of calibre between 28 and 30 r for example.

With regard to the firearm as a whole, it comprises a substantially cylindrical breech mechanism 1 adapted to be displaced in a translatory movement in a breechcase 2 having towards the rear an interior shape and an exterior shape which are substantially rectangular (see FIG. 4), the small sides of v this cross section being designated by 3 and 4 and the large sides by 5 and 6. The breechcase 2 has, on the small side 3, an ejection passage 7 for the empty cartridge cases, and on the two large sides 5 and 6, introduction openings 8 for the introduction of cartridges coming from two feed mechanisms 9 which can be alternately put into position for firing. A helical counterrecoil spring 10 is provided between the breech mechanism 1 and the rear part of the breechcase 2.

With regard to the breech mechanism 1, it is advantageously constructed according to the above-mentioned U.S. Pat. Such a breech mechanism comprises a breechblock 11 which is locked by rotation and which comprises on the one hand, at its front part, a cup-shaped recess 12 in which the rear ends (not shown) of the cartridges to be fired come into engagement, and on the other hand, exteriorly, locking lugs 13 which cooperate with lugs 14 formed on a sleeve 15, which receives the barrel 16 in a removable manner due to a bayonet joint 17. The breech mechanism 1 also comprises a casing 18, formed of two casing elements in the form of shells separated approximatively by the plane of FIG. 1. The casing 18 can slide without rotating in the breechcase 2 and is disposed around the breechblock 11. This breechblock passes through the casing 18 at the rear in a manner to cooperate with the usual breech damping device 19, situated at the rear of the breechcase 2. A spindle 20 passes through the breechblock 11 and is connected, inside this breechblock, to the firing pin 21 and, at the exterior of this breechblock, without play, to the casing 18. The lugs 13 of the breechblock 11 are situated on the same cylinder of revolution as a part at least of the exterior surface of the casing18," which permits the breechblock 11 to be guided by the contact of the casing 18 and of at least some of its lugs 13 with thesarhe surface (which will be more explicitly described hereafter). A spring 111 acting on the firing pin 21 tends to push the unit formed by the firing pin 21 and the casing 18 towards the front of the breechblock l 1.

In order to transform into a rotary movement of the breechblock 11, the translatory movement which is produced between the casing 18 and this breechblock when the breechblock arrives substantially at the position of closing shown in FIGS. 1 and 2, the spindle 20 carries two cylindrical rollers 22 cooperating respectively with skews 220 formed in a cylindrical enlarged portion 23 of the breechblock 1. 1.

At its exterior surface, the casing 18 carries two longitudinal projections 24 and 25 whose longitudinal lateral faces 24a and 25a cooperate with the interior faces of the large sides and 6 of the breechcase 2 (see FIG. 4) to prevent the casing from turning at the interior of this breechcase. The projection 24 comprises a front face 24b adapted to cooperate with a sear 26 for stopping the breech mechanism in the open position. The projection 25 comprises a front face 25b adapted to cooperate, on the one hand, with an unlocking pushpiece 27 (actuated in the manner described hereafter by tapping the gases in the barrel 16) which is provided for unlocking the breech mechanism 1 with respect to the breechcase 2, and on the other hand with a recocking device which permits the breechblock 11 to be brought back towards the rear after the breechblock has been stopped in the closing position. Such a recocking device can comprise a chain 28, one link of which carriers a hook for the face 25b. The chain 28 is stretched between a front idler pinion 29 and a rear pinion 30 fixed on a spindle 31 rigid with a crank 32. The projection 25 further cooperates by the rear with an ejector 33, mounted on a transverse spindle 34, for the purpose of making it tip, the projection 25 having a longitudinal groove 250 for the passage of the ejector.

Between two of its lugs 13, the breechblock 11 carries an extractor 35, and on the diametrically opposed side, it has a groove 36, for the passage of the ejector 33, which leads into the cup-shaped recess 12. The extractor can be maintained in place by a leaf-spring 37.

To maintain the casing 18 imperatively in its extreme rear position with respect to the breechblock 11 during the reciprocating movement of the breech mechanism 1 inside the breechcase 2, a leaf-spring 38, carried by the breechblock 11, tends to project by its rear part against a bearing face 39 of the casing 18. An inclined surface 40, carried by the breechcase 2, can retract the leaf-spring 38 by acting on a pushpiece 41 passing through the casing 18.

That being the case, according to a first feature of the invention, the part 3-6 of the breechcase 2 that is of substantially rectangular cross section has, at the level of the cartridge introduction openings 8, four guiding surfaces 42 for the breech mechanism 1 (casing 18 and lugs 13) as well as for the counterrecoil spring whose exterior diameter is substantially equal to the diameter D of the breech mechanism, these guiding surfaces 42 being situated on a cylinder of revolution about an axis parallel to the axis X-X of the barrel l6 and generally coincident with this axis XX. The trace of this cylinder on the plane of FIG. 4 is coincident with the exterior contour of the casing 18 which is also the exterior contour of the spring 10.

According to an advantageous embodiment of this feature of the invention, the part of substantially rectangular cross section 3-6 of the breechcase 2 is extended towards the front by a part 43 whose interior and exterior cross sections are cylinders of revolution about the axis X-X of the barrel 16; the part 43 receives the sleeve to which the barrel 16 is fixed in a removable manner; the annular space left free between the exterior of the sleeve 15 and the interior of the cylindrical part 43 of the breechcase 2 houses the control devices of the feed mechanism or mechanisms 9 (which control devices will be described below), the damping devices for the recoil and the return to firing position and the breech mechanism unlocking device with its pushpiece 27.

The passage 7 and the openings 8 extend towards the front to the front end of the sides 3, 5 and 6. The small side 4 is approximatively tangential to the cylindrical part 43. This part and the elements of each large side 5 and 6 that exist on both sides (in the transverse direction) of the openings ii are connected among themselves by transverse partitions 61 that render the breechcase 2 rigid and assure its fluidtightness.

It is supposed in the following that the breechcase 2 is fixed and that the unit formed by the sleeve 25 and the barrel 16 can recoil with respect to this breechcase in the interior of which it is guided. The damping devices for the recoil and for the return to firing position can be of two types, mechanical and hydraulic. The mechanical damping devices, which are five in number in the embodiment represented, each comprise a helical spring 44, coiled around a telescopic guide 45 parallel to the axis X-X of the barrel 16, which bears, at the front, against a collar 46 integral with the sleeve 35, and at the rear, against a ring 47 rigid with the breechcase 2. This ring 47 can be maintained against a shoulder 42 of the breechcase not only by the springs 44 but also by rods 5) fixed by one end to this ring, passing freely through the collar 46 and bearing by the other end on a nut 50 screwed on the front of the breechcase 2. The hydraulic damping devices, which are two in number in the embodiment represented, comprise oil dash-pots each comprising a cylinder 51 coupled to the ring 47 and a piston whose piston-rod 52 is coupled to the collar 46, although of course the pistons and cylinders can be interchanged.

The unlocking device, with its pushpiece 27, for the breech mechanism 1 can comprise a cylinder 53, backed onto the collar 46, and a piston or plunger 54 rigid with the pushpiece 27. The cylinder 53 is connected by a conduit 55, comprising a throttle device 56 (that is to say a body traversed by a channel whose cross section permits the regulation of the operation of the device by constriction of the gases), to a zone of the barrel 16 situated at a certain distance from the cartridge chamber 57. The unit formed by the pushpiece 27 and the piston or plunger 54 is returned towards the front by a spring 58, the pushpiece 27 and this spring passing through the ring 47 through an opening visible at the bottom of FIG. 1.

In the annular space left free between the exterior of the sleeve 15 and the interior of the cylindrical part 43, the damping devices for the recoil and for the return to firing position and the unlocking device for the breech mechanism 1 can occupy the lower sector, as shown in FlG. 3, the unlocking device being advantageously placed in a manner to separate these damping devices into two approximatively symmetrical groups. in the space in question, a guiding key 59 can be disposed, rivetted to the breechcase 2, and lying without play in grooves which pass through the collar 46 and the ring 47 parallel to the axis X-X thus preventing them from rotating about this axis. In particular, it will be understood that at the firing of a round, the starting of the rotation of the projectile, by penetration of the helical lands of the barrel 16 into the driving-band of the projectile, generates, by reaction, in the unit formed by the barrel and the sleeve 15, a torque which is absorbed by the key 59, which prevents this unit from rotating in the interior of the breechcase 2.

To the rear of the introduction openings 8, the large sides 5 and 6 of the part of substantially rectangular cross section of the breechcase 2 are closed by coaxial curved parts 60 whose interior diameter is equal to the diameter D of the breech mechanism 1 and which are adapted to render the breechcase 2 fiuidtight and rigid, while guiding the breech mechanism 1 and the counterrecoil spring 10. In FIG. 4, the central zone of the curved parts 60 can be seen through an opening 62 in the transverse partitions 61, the interior contour of these parts 60 being coincident with the exterior contour of the casing 18 (which is also the exterior contour of the spring 10).

The interior width indicated by the arrow 0, between the large sides 5 and 6, is larger than the maximum diameter of the cartridge cases (so that these cartridge cases can pass through the passage 7) and smaller than, but as near as possible to the diameter D of the breech mechanism (to permit the curved parts 60 to be fitted in place).

The curved parts 60 are extended at the rear, beyond the part of substantially rectangular section 3-6, by two cylindrical sectors 63 provided with bayonet lugs 64 and adapted to receive a closing block 65 which serves as a support for the counterrecoil spring and contains the damping device 19 of the breech mechanism. In addition to a cylindrical part 65a which fits partially on the sector 63, and a back which is comprised by an element of the device 19, the block 65 comprises at the front two radial wings 65b adapted to block off the zones of the part of substantially rectangular cross section 3-6 which are not covered by the cylindrical part 65a.

At the interior of the part of substantially rectangular cross section of the breechcase 2 and in the neighbourhood of the

small sides

3 and 4 of this cross section, there can be disposed, at the exterior of the volume swept by the breech mechanism 1, supplementary mechanism such as the sear 26 and its damping spring 66, the ejector 33 and the recocking mechanism 28-31). A cam 67 serves to retract the sear 26 against the ac- 'tion of a spring 68.

It is advantageous to make the breechcase 2 carry exter nally, on one of the small sides of its substantially rectangular cross section, for example on the side 4, at least one spindle or rod of articulation 69 for the alternate placing of the feed mechanisms 9 in firing position, and on the other small side 3, the mechanism controlling the rotation of the feed mechanisms about this rod 69.

With regard to the fastening and the control of the feed mechanisms 9, they are advantageously arranged as in my US. Pat. application Ser. No. 622,643 filed Mar. I3, 1967. For this purpose, the two feed mechanisms 9 are mounted so that they can rotate about an axis Y-Y parallel to the axis X-X of the barrel 16. The axis of rotation Y-Y is materialized by a hinge 70 assembled by the rod 69. The mechanisms 9, which are in general belt feed mechanisms, are each provided with a cover 71 which can rotate about a hinge 72, with respect to a casing 82 fixed directly to the small side 4 of the breechcase 2, in order to permit the transverse introduction of the cartridge belt. Each cover is normally locked by a hook 73.

The mechanisms 9 are coupled by a fork 74 guided on the small side 3 in a manner that it can slide transversely with respect to the firearm. The fork 74 has slots 75 which each cooperate with a catch 76 rigid with the feed mechanism being considered. A slider 77, guided longitudinally on the small side 3, actuates a lever 78 which is carried by a spindle 79 passing through the slider through an elongated slot. This lever has a curved head 78a, in the form of a dovetail, which is engaged in a mortise 74a of the fork 74. When the gunner displaces the slider 77 longitudinally in one direction or the other, it rocks the lever 78 about the spindle 79 and displaces the fork 74 transversely (toward the left of FIG. 4 if the position shown is the starting position), which puts out of action the feed mechanism 9 (at the left of FIG. 4) which was in firing position, and puts in action the other feed mechanism, by rocking about the rod 69.

Each feed mechanism 9 has a mechanism for belt advancement and for motion transmission housed in the casing 82 of the feed mechanism and a driving member adapted to be displaced in a direction substantially parallel to the axis X-X of the barrel 16 of the firearm. According to the embodiment represented in FIG. 2, the belt advancement mechanism corn prises cartridge-pushing pawls 80 and the motion transmission mechanism for transmitting motion to these pawls in comprised by a lever 81 adapted to pivot about a spindle 83 and having a driving projection 34. The advancement mechanism can be of any type, for example as described in US. Pat. No. 3,198,075. Furthermore, the driving member of the feed mechanism is comprised by a roller 85 which is carried by one of the arms of a two-armed lever 86. The other arm of this lever carries a second roller 87 situated in the trajectory of the projection 84, the lever 86 pivoting about a spindle 88 parallel to the spindle 83. The arm of the lever 86 that carries the roller 85 is oriented in a manner such that this roller describes a circular are practically identical with its tangent that is parallcl to the axis X-X. It can be seen that, if the roller 85 is pushed towards the right of FIG. 2, it makes the lever 86 rock in the direction which raises the roller 87 with respect to the plane of FIG. 2, which makes the lever 81 rock in a manner such that its free end is displaced in the same direction. At least one spring (not shown) assures the return of the

levers

81 and 66 by maintaining the roller $37 in contact with the projection 84.

For two such feed mechanisms, according to a second feature of the invention, the firearm comprises a single motor member having alternating longitudinal movement and connected to a recoiiing part of the firearm, this motor member having a form and a position such that it meets, during its active or recoil movement, only the driving member 135 of the feed mechanism 9 that is in firing position.

According to a particularly advantageous embodiment of this feature, the motor member has the form of a fork 89 whose base 890 is oriented towards the front and cooperates with longitudinal guiding surfaces and whose two branches 89b cooperate by their rear part respectively and alternately with the driving members or rollers of the feed mechanisms. The fork 89 has a transverse portion 89c interconnecting the base 89a and the branches 8%. In each casing 82, a passage 90 is provided opposite the roller 85 for the corresponding branch 8912. It can be seen in FIG. 4 that the right feed mechanism, which is out of action, has its passage 99 out of the trajectory of the corresponding branch 8%, this branch passing freely into a notch 91 formed in the casing 82. On the contrary, the feed mechanism visible at the left of FIG. 4, which is in action, has its passage 90 just opposite the corresponding branch 89b, such that only this branch meets the roller 85 that is associated with it and can thus actuate the feed mechanism 9 that is in action.

It has been explained above that the control device of the feed mechanisms 9 are placed, with other members, in the annular space left free between the exterior of the sleeve 15 and the interior of the cylindrical part 43 of the breechcase 2. These control devices comprise essentially the fork 9, whose transverse portion 89c is curved to conform, to the sector of the annular space that it occupies (see FIG. 3), as well as compression springs (with their guides) which are described below.

As it has just been explained, the sleeve 15 essentially forms with the barrel 16 the recoiling part of the firearm whose breechcase 2 is fixed. The fork 89 is guided at the front by the collar 46 forming a part of the sleeve 15, due to a notch 92 through which the front end of the base 89a passes without appreciable lateral play. The front end of the base 39a can be maintained radially against the bottom of this notch by contact with the interior wall of the cylindrical part 43 of the breechcase 2., as can be seen at the top of FIG. 1. Furthermore the fork 89 is guided at the rear by a member fixed with respect to the breechcase 2, this member being advantageously comprised by the ring 47. For this purpose, this ring can comprise a bore 93 parallel to the axis X-X and adapted to guide an extension 89d of the base 89a, situated towards the rear beyond the transverse portion 89c. The ring 47 furthermore comprises a central bore 98 for guiding the rear of the sleeve 15. The base 69a can carry a shoulder 89s adapted to cooperate by abutment with the rear face of the collar 46 of the sleeve 15.

Between the fork 89 and the collar 46 acts at least one compression spring adapted to make the fork recoil with respect to.

the breechcase 2, abutment means being provided for bringing back the fork into firing position during the forward return of the recoiling part 15, 16 of the firearm. I

As can be seen in FIGS. 2 and 3, two compression springs 94, each wound around a telescopic guide 95 parallel to the axis X-X, are disposed on both sides of the base 89a, these springs bearing at the rear against the transverse portion 896 of the fork.

The abutment means for bringing back the fork into firing position comprise, preferably, a double shoulder 96 provided at the end of the base 39a, in front of the collar 46, and adapted to abut against the front face of this collar.

FIG. 3 shows that in front of the transverse portion 89c the annular space defined hereabove receives the base 89a, four springs 94 with their guides 95, two hydraulic damping

devices

51 and 52, five mechanical damping devices 44 and 45, and the unlocking device 53 and 54 for the breech mechanism. To the rear of the transverse portion 89c, the springs 94 with their guides 95 are absent and the base 890; is replaced by the branches 89b and the extension 89d.

The interior of the base 39a of the fork can be in the form of a cylinder forming part of a dash-pot regulator for regulating the recoil speed of the fork, this recoil being accompanied by the relaxation of the springs 94. For this purpose, the base 89a is provided with a bore 97, parallel to the axis X-X, in which two

pistons

99 and 100 can slide and are mounted one behind the other, with a certain axial play, on a rod 101. This rod passes in a liquid tight manner rearwardly through the bottom of the cylinder formed by the bore 97 and bears, preferably by means of the ring 47, against a stop 102 rigid with the breechcase 2. An annular sealing ring 103, disposed in a slidable manner about the rod 101, is pushed by a spring 104 towards the two

pistons

99 and 100, and the space situated in the bore 97 in front of the sealing ring 103 is filled with oil. It can be seen that the spring 104 has the effect of maintaining in this space a pressure sufficient to push the rod 101 into contact with the stop 102 and permits, moreover, the sealing ring 103 to be displaced to compensate for the variations of volume of this space which are due to the larger or smaller penetration of the rod 101. Between the front piston 100 and the bore 97, play is provided which normally assures a constant speed of recoil of the fork 89 by passage of the oil from the front to the rear of this piston. The piston 99 carries elastic rings 105 which tend to separate the piston 100 from the piston 99. The piston 100 has channels 106 passing therethrough adapted to be blocked off by the neighbouring face of the piston 99 when the piston 99 is in contact with the piston 100. It can be seen that, if the speed of recoil of the fork 89 (towards the right of FIG. 1) increases, the pressure prevailing in front (to the left) of the piston 100 increases and this piston compresses the rings 105 and comes into contact with the piston 99. This closes the channels 106 and the oil can only pass through the annular play provided at the periphery of the piston 100. The recoil of the fork 89 is thus well braked whereas its advance is not braked, in particular by reason of the one-way action between the rod 101 and the stop 102.

Returning to the mechanism, including its lever 86, for motion transmission between the fork 89 and each feed mechanism 9, it is housed in the casing 82 which is connected directly to the breechcase 2 whereas the mechanism, having the lever 81 and the pawls 80, for the advance of the belt, is housed in the cover 71. The spindle 88 of the lever 86 is thus fixed to the casing 82 in which the passage 90 is formed, whereas the spindle 83 of the lever 81 is fixed to the cover 71. It will be understood that the coupling, by the projection 84 and the roller 87, between the two levers 86 and 81 permits opening and closing of the cover 71, for the transverse introduction of the cartridge belt, without any particular precaution.

Advantageously, the breech mechanism is arranged in a manner such that the rear of the motor member or fork 89, in the rest position illustrated in FIG. 2, is located in front of the front face of the feed mechanisms. In other words, when the sleeve 15 is in its most forward position and when the shoulder 96 of the fork 89 is in abutment with the collar 46, the rear end of the one of the branches 89b that is located opposite a roller 85 does not penetrate into the corresponding passage 90. This permits the two feed mechanisms 9 to be rocked in the manner described above without the branches 89b of the fork 89 hindering this manoeuvre.

In the foregoing, a firearm has been described comprising at the interior of a breechcase 2, on the one hand, a sleeve 15 to which the barrel 16 of the firearm is fixed in a removable manner by a bayonet joint 17, and on the other hand, an annular connecting member in the form of a nut 50 which is screwed on the front of the breechcase 2 and which serves to maintain the sleeve 15 in the longitudinal direction towards the front and in the transverse direction at the same time, connecting means 55 and 56 being provided between the part of the barrel 16 and/or the sleeve 25 situated at the front of the nut 50 and a zone situated at the rear of the sleeve 15 between this sleeve and the breechcase 2.

in this firearm, the sleeve 15 is adapted to recoil with the barrel in with respect to the breechcase 2 and is guided in translation by the nut 50.

According to a third feature of the invention which could, should the occasion arise, be used in firearms in which the breechcase 2 participates in the recoil and/or in which the connecting means are of another nature than a conduit for the gases, the sleeve 15 has two successive collars, namely a front collar 107, whose diameter is equal to the interior diameter of the nut 50 and which is disposed in the interior of the nut whereby the sleeve 15 is maintained transversely with respect to the nut (with sliding, according to the embodiment represented), and a rear collar whose diameter, greater than the diameter of the front collar 107, is equal to the interior diameter of the breechcase 2 and which is disposed to the rear of the nut 50 whereby forward movement of the sleeve i5 is limited by the nut 50 (by abutment), and the sleeve 15 is maintained longitudinally with respect to the nut 50 (by abutment) and transversely (with sliding) with respect to the breechcase 2. ireferably, this rear collar is the collar 46. Moreover, the interior diameter of the nut 50 is chosen sufficiently large (in other words, the radial thickness of this nut sufficiently small) to permit an intermediate element of the connecting means in this case the throttle device 56, to pass through the front collar 107 without touching the nut 50.

The sleeve 15 is thus guided, at the front, by contact with the interior surfaces of the nut 50 (collar 137) and of the breechcase 2 (collar 46), and at the rear, by contact with the bore 98 of the ring 47. Its movement towards the front is limited by contact of the front face of its collar 46 with the rear face of the nut 50. A retractabie locking device 108, having a ball or the like, prevents the nut from turning with respect to the breechcase 2.

Due to the arrangement of the nut 50 which has just been described, it can be seen that it is possible to screw it or unscrew it, with a view to dismantling or reassembling the sleeve 15, without preliminary dismantling of the connecting means and more particularly, according to the example shown, of the throttle device 56.

In the foregoing, an ejection system has been briefly described which comprises an extractor 35 carried by the movable breech mechanism l, and diametrically opposed, an ejector 33 carried by the breechcase 2 and actuated by the breech mechanism 1, by contact of the tail 33a of the ejector with the projection 25 of the breechblock 11.

More precisely, the ejector 33 comprises at the front a transverse striking surface 109 (FIGS. l and 5) for the rear edge of the empty cartridge case 110 to be ejected and it is controlled by the breech mechanism in the usual manner such that it presents the striking surface 109 into the trajectory of this rear edge during the recoil of the breech mechanism. To simplify the drawings, the lugs 13 of the breechblock 11 have been omitted in FIG. 5.

According to a fourth feature of the invention, which can be applied whatever be the nature of the breech mechanism, and in particular, of its locking means (by rotation as described with the aid of separate locks), the ejector 33 comprises, at the front of the striking surface 109, a projection 112 adapted to strike the lateral surface of the cartridge case 110 transversely, before the impact with the rear edge of the cartridge case. FIG. 5 shows the cartridge case 110 which, still maintained at the top by the extractor 35 after having been struck by the projection 112, has begun its tipping movement in the direction of the ejection passage 7. It is only then that the striking surface 109 hits the rear edge of the cartridge case,

anunin nn lo with a relative speed which is decreased by the forward speed imposed on the part of this edge that the surface 109 strikes. In this manner, the violence of the impact is decreased and the ejection trajectory is stabilized.

The operation of the firearm described above is the follow- 5 When a cartridge is placed in the chamber 57 and when the breech mechanism arrives in the position of FIGS. 1 and 2, the cartridge is fired, which causes the recoil of the unit formed by l the barrel 16, the sleeve 15 and the breech mechanism 1. By the rear of the collar 46 of the sleeve, 15, the recoil damping springs 44 and the control springs 94 of the feed mechanisms are compressed and the pistons of the

recoil dampers

51 and 52 are driven towards the rear. The springs 94 drive the fork l 5 89 towards the rear with a speed regularized by the dash-pot 97 and 99-105, whatever be the resistance to the traction of the belt in the one of the two feed mechanisms 9 that is in firing position. According to the stroke of recoil of the firearm, the collar 46 of the sleeve abuts or does not abut against the shoulder 892 of the fork'89. By the one of its branches 89b which meets a roller 85, the fork makes the levers 86 and 81 of the feed mechanism in firing position pivot, which puts a cartridge in position for introduction.

When the bullet has passed the gas inlet of the conduit 55, the gases pass through the throttle device 56, penetrate into the unlocking cylinder 53 and act on the front face of the piston or plunger 54. This piston or plunger 54 compresses the spring 58 and drives the breech mechanism casing 18 in an ac celerated movement. The casing 18, while recoiling, makes the breechblock 11 rotate in a manner such that it frees itself from the sleeve 15. The residual pressure of the gases in the chamber 57 contributes to make the breechblock ll recoil, which it does while compressing the counterrecoil spring 10, the breechblock 11 finally abutting at the end of its stroke against the damping device 19. At the same time, the empty cartridge case is ejected in the manner described above.

The breech mechanism is then returned towards the front by the damping device 19 and the counterrecoil spring 10, drives the cartridge that was in position for introduction and introduces it into the chamber 57. The casing 18, which had been maintained at the rear of the breechblock 11 by the leafspring 38 during the reciprocation of the breech mechanism, is freed by the action of the inclined surface 40 and the spring 111 drives it towards the front, which, on the one hand, locks the breechblock 11 by making it rotate and then brings the point of the firing pin 21 into the cup-shaped recess 12 (new percussion). Y

During the forward return of the breech mechanism, the springs 44 restore their energy while bringing back towards the front the sleeve 15 and the barrel 16. The fork 89 is driven positively towards the front by abutment of the shoulder 96 against the collar 46 and is also driven in this direction by the springs 94. The damper 97 and 99l02 is inoperative during this forward stroke, for the reasons explained above (separation of the

pistons

99 and 100, absence of positive coupling between the rod 101 and the abutment 102). On the contrary however, the

dampers

51 and 52 brake the recoil as well as the a reduced cumbersomeness, since the two feed mechanisms 9 are disposed on parts of the breech mechanism that are narrowed by a substantially rectangular cross section;

a simple putting out of action of the retracted feed mechanism, since it depends only on the position of this feed mechanism;

a gain of energy in the driving of the feed mechanism into its firing position since the only members in motion are those which transmit directly the recoil energy to this feed mechanism;

a great facility of dismantling of the firearm due to the construction of the nut 50;

a great safety of operation due to the fact that all the moving members are housed at the interior of a fluidtight breechcase.

Although the invention has been described with particular reference to a preferred embodiment, it should be understood that the invention is not limited thereto, and that various modifications and changes are possible without departing from the spirit and scope of the invention.

I claim:

1. A firearm of the type having a breech mechanism movable within a breechcase at least between a load position and a firing position comprising: a barrel removably attached to a sleeve, a portion of the breechcase surrounding the sleeve and spaced therefrom by a front collar and rear collar, both of which collars are fixidly connected to the sleeve, an annular connecting member having means on its exterior surface for removably attaching the annular connecting member to the interior surface of the front end of the breechcase, the rear surface of the annular connecting member engaging the rear collar at least when the sleeve is in its rest position, the exterior diameter of the front collar being substantially equal to the interior diameter of the annular connecting member and the exterior diameter of the rear collar being greater than the interior diameter of the annular connecting member and substantially equal to the interior diameter of the breechcase, and including an actuating mechanism connected to the barrel, a portion of the actuating mechanism passing through the collars for carrying out an auxiliary function in the firearm, the position of the annular connecting member being such that removal of the annular connecting member renders'the sleeve, the barrel and the actuating mechanism removable, as a unit, from the firearm, without first dismantling the actuating mechanism.

2. A firearm according to claim 1, wherein the said means on the exterior surface of the annular connecting member comprises screw threads which cooperate with mating screw threads on the interior of the breechcase for removably attaching the annular connecting member to the breechcase.

3. A firearm according to claim 1, wherein said portion of the actuating mechanism includes a conduit connected to said barrel and adapted to transmit gases from said barrel for carrying out said auxiliary function.

4. A firearm according to claim 3, including a breech mechanism casing, and piston means between the conduit and the breech mechanism casing, and wherein the gases passing through the conduit after the gun is fired act upon the said piston means to move the breech mechanism casing rearward relative to the barrel.

5. A firearm according to claim 4, including a breechblock mounted in said breech mechanism casing for forward and rearward movement relative to the breech mechanism casing, and wherein after the said casing starts to move rearwardly under theinfluence of said gases passing through the conduit, the residual pressure of the gases in the barrel acts directly on the breechblock to contribute to make the breechblock recoil.

6. A firearm according to claim 3, in which said breech mechanism comprises a casing and a breechblock, said casing being mounted in said breechcase for forward and rearward sliding movement, without rotation, relative to said breechcase and relative to said barrel, and said breechblock being mounted in said casing for forward and rearward movement relative to said casing, said breechblock being arranged to be locked and unlocked, by rotation, with respect to said barrel, and said casing being arranged such that during its rearward movement relative. to said barrel, it rotates and hence unlocks said breechblock, and including piston means between the conduit and the casing, and wherein the gases passing through the conduit after the gun is fired act upon the said piston means to move the casing rearward relative to the barrel.

ranged such that after the said casing starts to move rearwardly under the influence of said gases passing through the conduit, the residual pressure of the gases in the barrel acts directly on the breechblock to contribute to make the breechblock recoil.