US2116140A

US2116140A - Firing mechanism for automatic firearms

Info

Publication number: US2116140A
Application number: US11792A
Authority: US
Inventors: Marriner A Browning
Original assignee: J M & M S Browning Co
Current assignee: J M & M S Browning Co
Priority date: 1934-04-10
Filing date: 1935-03-19
Publication date: 1938-05-03
Anticipated expiration: 1955-05-03
Also published as: US2116139A

Description

2 Sheets-Sheet l Wm@ m l@ l 1m May 3, 1938. M. A. BRowNlNG FIRING MECHANISM FOR AUTOMATIC. FIREARMS Original Filed April l0, 1954 May 3, 1938. M A. BRowNlNG FIRING MECHANISM FOR AUTOMATIC FIREARMS Original Filed April l0, 1954 2 Sheets-Sheet 2 Patented May 3, 193s 'UNITED y STATES PATEN OFFICE ARMS Marriner A. Browning, Ogden, Utah, assignor to 'J. M. & M. S. Browning Company, Ogden,

Utah, a corporation of Utah original application Ap'ru 10, 1934, serial No..

Divided and this application March 19, 1935, Serial No. 11,792 i 20 Claims.

' The principal object of the invention is to provide an improved retarding mechanism whereby the gun may be caused to operate at a slower speed than it otherwise would.

' Another object is to provide a construction whereby the several parts of the firearm may 'be quickly and easily assembled or disassembled.

A still further object of the invention is to provide a construction whereby movement of the 10 sear into its operative position is of a snap-action character.

This present application constitutes a division of my co-pending application for Automatic fire.- arm, Serial No. I719,862, filed April 10, 1934, which 15 said co-pending application was issued as Patent No. 2,093,704 on September 2l, 1937.

In the accompanying drawings I have shown the embodiment of the invention which I now deem preferable, but it will be understood that o the drawings are intended for illustrative purposes only and are not to be relied upon as limiting or defining the scope of the invention, the claims forming a part of this specification being relied upon for that purpose.

25 Of the drawings:

. Fig. 1 is a side view of a firearm embodying the invention.

Fig. 2 is an enlarged fragmentary view of the rear portion of the firearm, this view being partly 30 a side view and partly a longitudinal sectional view.

Fig. 3 is a view similar to Fig. 2 but showing the parts in different relative positions.

Fig. 4 is a fragmentary sectional view taken 35 along the line 4 4' of Fig. 3.

Fig. 5 is a detail view showing an intermediate position to which the action spring yoke is moved during disassembly of the gun.

Fig. 6 is an enlarged plan view of the trigger 40 and retarding mechanism shown in Figs. 1, 2

and 3.

Fig. '7 is a fragmentary View similar to Fig. 6 but showing the parts in different relative positions.

Fig. 8 is a fragmentary longitudinal sectional view taken along the line 8-8 of Fig. 6.

Fig. 9 is a longitudinal sectional view takenv along the line 9-9 of Fig. 6.

Fig. 1.0 is a view similar to Fig. 6 but showing 50 the parts adjusted to render the retarding mechanism ineffective.

Fig. 11 is a fragmentary longitudinal sectional View taken along the line II-II of Fig. 10.

Fig. 12 is a fragmentary longitudinal sectional 55 view taken along the line I2-I2 of Fig. 10.

plate 1 in place.

Fig. 13 is a rear view of the trigger and retarding mechanisms.

Fig. 14 is a view similar to Fig. 13 but showing the parts in different relative positions.

. Referring to the drawings, I represents as an entirety the main breech casing which is generally rectangular in transverse section. As shown, the casing is formed from a single piece of steel although I do not necessarily limit myself to this integral construction. The portion I a of the casing is formed to receive the rear end of a barrel 2. Behind the portion I are two main side walls connected near the center by an integral cross member I". An opening is provided at the front of the cross member I, which opening is normally closed by a pivoted cover 3 held by a releasable latch 3'. The bottom of the casing is normally closed by separate front and rear plates. The rear of the casing is normally closed by a plate 1 flanged at its sides and having ribs adapted to enter grooves formed inthe side walls. A suitable latch serves to normally hold the end Carried by the plate 1 at oppositegsides thereof are brackets 8 carrying handles 'I'he casing I is provided with an integral extension Ie which extends forward underneath the barrel. 'I'his extension is hollow and it serves to engage and retain a piston tube I 6. At its forward end the tube I6 is connected with, and supported by, the barrel. Longitudinally movable along the bottom of the main casing is an operating slide 21, this slide being connected with a piston rod 28 and a piston 29 positioned within the piston tube I6. A cylinder 3| is provided in the forward end of the tube I6, and the piston accurately fits the said cylinder. A gas passage extends from the bore of the barrel to the cylinder, to enable the gases of explosion to enter the cylinder and act upon the piston to force it rearward. For returning the slide in the forward direction after having been moved rearward by the piston and piston rod, there is provided an action spring |32.

Extending transversely through the casing below the rear portion of the barrel is a cartridge feed channel 31 adapted for the reception of a cartridge belt such as A. Transversely movable below the feed channel 31 is a feed slide 39, which is actuated by means of the operating slide 21. As shown, the main portion of the feed slide is below the operating slide, and in this case the operating slide has a cam groove in its lower face into which projects a pin carried by the feed slide. The shape of the groove is such that the slide 21, this mechanism being similar to that` disclosed in Patent No. 1,293,022 to John M. Browning. As shown in Fig. 3, the breech bolt 45 is connected with the slide 21 by means of two links 46 and 41 pivotally connected with each other at 48. The link 46 is pivotally connected with the breech bolt at 49 and the link 41 is pivotally connected with the slide at 50. When the slide 21 is in its rear position, as shown in Fig. 3, the two links 46 and 41 are held substantially in alignment in the relative positions shown. A lug 41al on the link 41 engages the link 46 to prevent downward movement beyond the position shown.

When the slide 21 moves forward under the inuence of the action spring |32 the two links 46 and 41 and the breech bolt 45 move in unison with it until the breech bolt nearly reaches its forward position, the link 46 being then approximately in register with the opening |d in the top wall of the casing. At or about the time that the link comes into register with the opening the curved portion 46b of the link 46 engages two cams 5| projecting inward from the respective side walls of the casing. In the drawings only the cam on the left hand side is clearly shown, but it will be understood that there is a similar cam on the right hand side. These cams 5| cooperate with the curved portion 46b of the link 46 to force the link upward into the opening Id, the rear end portion of the link abutting against the rear wall of the opening, as clearly shown in Fig. 2. In the meantime the slide 21 has continued its forward movement, thus bringing the link 41 into a substantially upright position. With the parts in the position shown and described, the breech bolt is firmly locked in its forward or breeched position and is well adapted to resist the recoil action incident to firing. Following ring the slide 21 is moved rearward by the action of the gases of explosion in the manner already described, the link 41 serving rst to draw the link 4B downward out of locking position and then to move the link 46 and also the bolt 45 rearward to the positions shown in Fig. 3.

It will be understood that the breech bolt 45 and the links 46 and 41 are removable with the slide 21 and the rod 28, all of these parts being removable as a unit.

A firearm incorporating the present invention is intended to be used with cartridges having annular grooves in the heads thereof, and the front end of the breech bolt-is provided with vertical ribs 52 which cooperate to form a vertical groove for receiving and retaining the heads of the cartridges. When the breech bolt is in its forward position, as shown in Fig. 2, the head of the cartridge which is in central position in the feed channel 31 is vertically below the groove in the front of the breech bolt. For withdrawing the cartridge from the feed channel and lifting it into proper relationship to the breech bolt there is provided an extractor 54. This extractor is provided with a pivot pin 55 which fits a transverse pivot opening in the breech bolt,

the extractor thus moving bodily rearward and forward as the breech bolt moves. The extractor `54 is providedl with a transversely extending tooth 56 which is so shaped and positioned as to enter the groove in the cartridge when the breech bolt and the extractor are in their forward positions, as shown in Fig. 2.

A suitable cam mechanism is provided for controlling and guiding the relative movements of the extractor, but as this cam mechanism constitutes no part of the present invention and is fully disclosed in my said application No. 719,862, it is not necessary to include a detailed description of it in this present specification. It is sufcient to say that when the breech bolt moves rearward the extractor moves rearward and upward, causing the cartridge to be extracted and then lifted into alignment with the chamber in the barrel. As the breech bolt returns in the forward direction, the cartridge is inserted into the chamber and the extractor is again moved downward into position to engage another cartridge in the feed channel.

A second extractor 69 is provided for extracting the empty shell from the chamber as the breech bolt moves rearward. This extractor serves in cooperation with the ejector to eject the empty shell from the ejection opening 18 in the right wall of the casing.

Preferably the operating slide 21 and the parts associated therewith are removable from the firearm at the rear thereof. To effect such removal it is necessary first to remove the action spring 32 in the manner to be presently described andto then remove the end plate 1 with the parts carried thereby. The slide is then substantially free to be withdrawn in the rearward direction, except for the fact that the pin on the feed slide must be disengaged from the groove in the operating slide. At the front of the bottom plate |30 there is provided a guide rod |3| which serves to support and guide the action spring |32. The rear end of the rod |3| is seated in a hole in the plate |30 and the forward end of the rod extends through a yoke |33 secured to the piston rod 28. 'I'he action spring abuts at the front against the said yoke |33. Through the medium of the yoke |33 the spring tends to move the piston rod 28 and the slide` 21 in the forward direction.

When the slide 21 and the associated parts are in their rearward position, as shown in Fig. 3,

the rod |3| and the spring |32 may be readilyv removed by first forcing the rod forward far enough to free it from the opening in the plate |30. 'I'hen the rear end of the rod can be lowered and the rod and the spring can be withdrawn in the rearward direction. In order that the slide 21 and the piston rod 28 may be withdrawn from the gun at the rear, in the manner already described, the yoke |33 is so constructed that it may be readily detached from the rod 28. As shown in Figs. 4 and 5, the yoke |33 has two ears |33, |33 which embrace the rod 28 and are formed with notches for receiving a transverse pin |35 forming diametrically opposed lateral projections on the rod. After the rod |3| and the spring |32 have been removed as already described, the yoke can be turned to the position shown in Fig. 5 and then it can be pushed forward and thus completely detached from the piston rod by these sequential movements of rotation and translation.

-The firing mechanism to which the invention more particularly relates will now bedescribed.

The slide 21 is formed with-an upstanding portion |38 which acts as a hammer` to directly engage the enlarged rear end of the firing pin |39, as clearly shown in Fig. 2. Thus i'lring is automatically effected as soon as the breech bolt and associated parts reach their forward positions, there being no separate and independently movable hammer. For retaining the slide 21 in its rearward position there is provided a sear 40 biased by a spring to operative position, that is, in engagement with a notch 21 in the slide and the sear is operable by a trigger |4| on the rear plate of the casing, which serves to move the sear to an inoperative position, that is, out of engagement with the slide. The sear |40 has a rearward extension |40 which is adapted to be engaged by a forward extension |4| on 'the trigger. The sear |40 is pivoted at |42 to a bottom plate |43.

In addition to the main sear |40 there is provided an auxiliary sear |44 also carried by the plate |43, this auxiliary sear being also engageable with the notch 21B. These two sears are preferably coaxially mounted at |42, but the sear |44 has an elongated slot |44a which permits it to move longitudinally through a limited distance for a purpose to be presently set forth.

vTo hold the sear |44 in engagement with the breech mechanism there is provided sear retaining mechanism. This mechanism may also be utilized as Asear releasing mechanism as will be apparent hereinafter. A spring |45 tends to hold the sear |44 in its rearward position, as shown in Fig. 9, and the said sear is further held by a forward projecting finger |44b thereon which engages a shoulder on an oscillatory abutment member |46 carried by a pivot pin |41. The member 46 may also have formed thereon the sear releasing cam surface as shown. Connected with the abutment member |46 is a forward projecting finger |48 which under certain conditions is obstructed by a laterally projecting arm of a bell crank or obstruction member |40 vertically pivoted at |50. A spring |5| serves to bias the member |49 in the clockwise direction and to tend to hold it in the position shown in Fig. 7. With the parts in the positions shown in Fig. 7 the member |40 prevents the nger |48 and the abutment member |46 from turning and the abutment member holds the sear |44 in its rearward position. The sear by reason of its engagement with the slide holds the said slide and its associated parts in the rearward positions, as shown in Fig. 3.

In order to reduce the rate of automatic re when desired, fire retarding mechanism may be provided for controlling the auxiliary sear |44. Longitudinally slidable in a recess in the plate |43 is a slide |52 comprising a body including an arm which is biased for vmovement toward the rear by means of a spring |53 carried by a guide rod |54. The slide |52 is provided with an upward projecting stud |55 which projects into a slot 21b in the bottom of the slide 21. When the slide 21 is in its rearward position, as shown in Fig. 3, the slide |52 is held by the spring |53 in its rearward position, as shown in Fig. 6; but when the slide 21 is in its forward position, as shown in Fig. 2, the rear end wall of the slot 21b is in engagement with the stud |55 and the slide |52 is'also in its forward position, as shown in Fig. 7.

Escapement means may be provided for retarding the speed of movement of the slide |52 to sear releasing position. Mounted on a vertical released by the sear |44,'the slide being entirely pivot pin |56 carried by the plate |43 is aratchet wheel |51 and an escapement wheel |50, these two wheels being connected together for movement in unison. Mounted on a pivot pin |50 is an escapement weight |60 having teeth thereon 5 which engage the teeth on the wheel |53. The teeth on the escapement weight are so related to the teeth on the wheel that the weight is forced to oscillate as the wheel is turned, thus the weight offers resistance to the turning of 10 the wheel.

Pivotally connected at |6| with the slide |52 is a ratchet arm |62 which is biased for movement in the clockwise-direction by means of a spring |63. The ratchet arm |62 has teeth there- 15 on adapted to engage with the teeth of the ratchet wheel |51, the teeth being held in engagement by reason of the bias of the spring |63. When the slide |52 is moved forward by the slide 21 to the position shown in Fig. 7 the ratchet 20 arm 62 moves with it, but the teeth thereof may snap over the teeth of the ratchet wheel |51 without causing any rotation of the said wheel.

When the 'slide 21 is moved rearward bythe action of the gases to operate the gun mechanism, the slide |52 does not move in unison with it, but, on the contrary, moves at a much slower speed, its movement being resisted and retarded by the engagement of the ratchet arm |62 with the ratchet wheel |51. During this rearward movement of the slide |52, the slide 21 and associated parts are held by the sear |44, these parts being so held even though the trigger |4| has been pressed so as to maintain the sear in its disengaging-position.

When the slide |52 reaches its extreme rearward position the end portion |52a of the said slide engages the rearward extending arm of the member |49 to turn the said member in the counter-clockwise direction to the position shown in Fig. 6. With the member |49 in this position the finger |48 is no longer obstructed and the abutment member |46 is free to turn in the clockwise direction. Still assuming that the sear |40 has been held in its disengaging position by means of the trigger |4|, the pressure exerted by the action spring |32 will move the slide 21 forward,

carrying the sear |44 with it and turning the abutment member |46. 'I'he cam surface on the member |46 in moving forces the sear |44 to move to the position shown in Fig. 8; and the sear in so moving releases the slide 21, permitting it to move forward and effect the ring of the cartridgein the manner already described. Fig. 8 shows the slide 21 in the position at which it is free to move forward. As the slide 21 moves forward the slide |52 is also moved forward, and the member |49 is restored by the spring |5| to its obstructing position, as shown in Fig. '1.

Preferably there is a cam |64 connected with the abutment member |46. When the parts are in the position shown in Fig. 8, the cam (although not shown in this figure) projects upward into the path of movement of the operating slide' 65 21. When the slide again mov-es rearward it engages the cam |64 to positively move the abutment member |46 and the sear |44 to their slide engaging positions, as shown in Fig. 9.

It will be observed that when the retarding mechanism is used the main Sear |40 normally has no control of the firing except to start and stop it. The rate of fire is controlled entirely by the auxiliary sear |44, the forward movement of the slide 21 being delayed for a short interval 75 following each shot and the rate of re being correspondingly reduced. v

In order that the retarding mechanism may be rendered inoperative when not required, there are provided certain additional parts which will now be described. Longitudinally movable on the plate |43 is a slide |65- which is vconnected by means of a stud |66 with a slide |61 longitudinally movable along guideways on the bottom of the plate |43. The slide |61 is provided with a nger piece |61a by means of which it may be moved, and the slide further has a manually releasable latch |68 by means `of which it may be held either in its rearward position, as shown in Figs. 8 and 9, or in its forward position, as shown in Figs. 10 to 12.

The slide |65 when in its rearward position is entirely ineffective, but when moved to its forward position the front end thereof engages the slide |52 to hold it in forward position, as shown in Figs. 10 to 12, The slide |65 is provided with an upward projection |65a which engages a cam surface |44c on the sear |44 to move it to a disengaged position, as shown in Figs. 11 and 12. With the part-s in the positions shown in Figs. 10 to 12 the retarding mechanism is entirely ineffective and the action of the gun is exactly the same as if the said mechanism were not provided.

When a sear such as the sear |40 is controlled entirely manually, there is the possibility that, when the operating slide is in its rearward position, the sear may be in intermediate position where it is uncertain whether it will or Will not suiciently engage the slide to hold it. The sear may momentarily catch and then by reason of vibration or otherwise may release the slide and cause the ring of an unexpected or unred shot. Toavoid these diculties it may be preferable to provide a latch or retainer for holding the sear in its fully disengaged position until the trigger is substantially fully released, the sear being then permitted to snap quickly to the position in which it fully engages the slide.

Referring particularly to Figs. 6, 8, 9, 13 and 14, it will be observed'. that there is provided a sear retainer B69 pivoted at |15 to a block |18. 'Ihis block is suitably secured in the recess in the plate |43 at the rear thereof and at the left side. A spring |12 biases the retainer |69 for movement in the counterclockwise direction. When the sear |40 is in its fully depressed position, as shown in Fig. 14, the retainer |69 projects over the edge of the rearward extension Ililia on the sear and holds the sear in its depressed position.

When the trigger |4| is released the forward extension |61!a thereof may move upward at least to the position shown in Fig. 14, without permitting any corresponding upward movement of the sear. When the position shown in Fig. 14 is reached, the extension |4 ia engages a cam surface |69a on the retainer and further upward movement-of the extension I4 |EL causes the retainer to swing toward the left, thus releasing the sear and permitting it to move suddenly upward to its engaging position1 as shown in Fig. 9.

As already stated, the trigger |4| is carried by the rear casing plate which is removable in the upward direction and replaceable in the downward direction. In order that the sear retainer |69 may not interfere with the downward movement of the rearward extension |4 |a on the trigger, it is provided with a cam surface |69b which is engaged by the said extension as it moves downward. This cam surface *|69b serves to move the retainer toward the left sufficiently tov let the trigger extension |4| move past it.

While I have shown the retarding mechanism in combination with a particular firing mechanism, it will be understood that I do not necessarily so limit myself and the said retarding mechanism may be combined with some other firing mechanism, such as shown in Figs. 2 and 3 of my said copending application Serial No. 719,862.

What I claim is:

1. In an automatic rearm including a sear,

fire retarding mechanism comprising in combination a slidable body, an arm on said body slidable therewith to and Afrom a sear releasing position, a second arm on the body, means for biasing the body to sear releasing position, and an escapement means cooperating with the second arm for retarding the speed of movement of the body to sear releasing position.

2. In an automatic rearm including a sear, fire retarding mechanism comprising in combination a slidable body, an arm on said body slidable therewith to and from a sear releasing position, a second arm pivoted to the body and extending in the same direction as the first arm and biased toward the latter, means for biasing the body to sear releasing position, and an escapement means positioned between the two arms and cooperating with the second arm for retarding the speed of movement of the body to sear releasing position.

3. In an automatic firearm, the combination of a sear, sear retaining mechanism movable to and from a sear releasing position, sear control means, means biasing said sear control means toward a position in which it engages and moves said sear retaining mechanism to its sear releasing position, and retarding mechanism connectedto the sear control means for regulating its speed of movement to sear retaining mechanism engaging position.

4. .In an automatic rearm, the combination nf a breech casing, a biased breech member, a sear mounted on the casing for pivotal and sliding movement to and from operative engagement with the breech member, a sear retaining and releasing member having a projection thereon engaging the sear to hold the sear in said operative engagement or to permit the sear to move the member and having a cam surface thereon for engagement with the sear to pivotally move the latter to an inoperative position uponmovement of the member by the sear, an obstruction member engageable with the sear retaining and releasing member to preventmovement of the same, and control mechanism engageable with the obstruction member to move it out of engagement with the sear retaining and releasing member whereby the biased breech member can slide the sear to cause the cam surface on the sear retaining and releasing member to pivotally move the sear out of engagement with the breech member.

5. In an automatic firearm, the combination of a sear, a trigger for releasing said sear, a second sear, sear control mechanism for said second sear, means for moving the sear control mechanism to a sear releasing' position, retarding means associated with said mechanism for regulating its speed of movement to sear releasing position, and means separate from said trigger for positively holding said second sear in an inoperative position While the firearm is being repeatedly fired in a fully automatic manner.

6. In an automatic firearm, the combination of a sear, sear control mechanism, means for moving the sear control mechanism to a sear releasing position, retarding means associated with said mechanism for regulating its speed of movement to sear releasing position, means for positively'holding the sear in an inoperative position while the firearm is being repeatedly fired in a fully automatic manner, and means for holding the sear control mechanism immovable.

7. In an automatic firearm, the combination of a sear, mechanism for effecting, and controlling movement of the sear to an inoperative position, said mechanism including means for delaying the movement of the sear to said inoperative position, movable means for selectively rendering the delaying means inoperative, and additional means for effecting movement of the sear to its inoperative position and for positively holding it in said position, said additional means being simultaneously movable with the said movable means.

8. In an automatic firearm, the combination of asear, mechanism for eecting and controlling movement of the sear to an inoperative position, said mechanism including means for delaying the movement of the sear to said inoperative position, and a single member for rendering the delaying means inoperative and for effecting movement of the sear to its inoperative position and for positively holding it in said' position.

9. In combination in an automatic firearm, breech mechanism automatically movable rearward upon flringand biased for automatic return movement to its forward position, firing means automatically operable when the breech mechanism reaches its forward position, a sear biased toward a position for engaging the breech Lmechanism to hold it in its rearward position,

mechanism including a longitudinally movable slide and serving when the slide is in its rearward position to cause the said sear to disengage the breech mechanism, means for causing the slide to be moved forward in unison with the' breech mechanism, means independent of the breech mechanism for moving the slide rearward immediately after its said forward movement, and means for retarding the rearward movement of the slide so that there is a predetermined interval between the automatic engagement of the sear with the breech mechanism and the disengagement thereof eiected by the slide.

l0. In combination in an automatic firearm. breech mechanism automatically movable rearward upon firing and biased for automatic movement to its forward position, ring means automatically operable when the breech mechanism reaches its forward position, a sear biased toward a position for engaging the breech mechanism to hold it in its rearward position, a movable member serving in one position to obstruct disengagement of the sear, mechanism including a longitudinally movable slide and serving when the slide is in itsV rearward position to move the said movable member out of its obstructing position so as to enable the scar to disengage the breech mechanism, means vfor causing the slide to be moved forward in unison with the breech mechanism, means independent of the breech mechanism for moving the slide rearward immediately after its said forward movement, and means for retarding the rearward movement of the slide so that there is a predetermined interval between the automatic engagement of the sear with the breech mechanism and the disengagement thereof enabled by the movement of the obstructing member.

' l1. In combination in an' automatic firearm, breech mechanism-automatically movable rearward upon firing and biased for automatic return movement to its forward position, firing means automatically operable when the breech mechanism reachesA its forward position, a sear biased toward aY position for engaging the breech mechanism to hold it in its rearward position, a movable abutment member for normally engaging the sear to prevent disengaging movement thereof, a movable member serving in one position to obstruct movement of the abutment member, a longitudinally movable slide serving in its rearward position to move the said obstructing member out of its obstructing position so as to enable the abutment member to move and permit the sear to disengage the breech mechanism, means for causing the slide to be moved forward in unison with the breech mechanism, means independent of the breech mechanism for moving the slide rearward immediately after its said forward movement, and means for retarding the rearward movement of the slide so that there is a predetermined interval between the automatic engagement of the sear with the breech mechanism and the disengagement thereof enabled by the movement of the obstructing member and of the abutment member.

12. In combination in an automatic firearm, breech mechanism automatically movable rearward upon firing and biased for automatic return movement to its forward position, ring means automatically operable when the breech mechanism reaches its forward position, a sear biased toward a position for engaging the breech mechanism to hold it in its rearward position, a movable abutment member for engaging the sear to prevent disengaging movement thereof, a longitudinally movable slide serving in its rearward position to enable the abutment member to move and permit the sear to disengage the breech mechanism, means for causing the slide to be moved forward in unison with the breech mechanism, means independent of the breech mechanism for moving the slide rearward immediately after its said forward movement, means for retarding the rearward movement of the slide so that there is a predetermined interval between the automatic engagement of the sear with the breech mechanism and the disengagement thereof enabled by the movement of the abutment member, and cam means associated with the abutment member and the breech mechanism for causing the latter to positively return the former to its sear engaging position.

13. In combination in an automatic firearm, breech mechanism automatically movable rearward upon firing and biased for automatic return movement to its forward position, firing means automatically operable when the breech mechanism reaches its forward position, a sear biased towarda position for engaging the breech mechanism to hold it in its rearward position, mechanism including a longitudinally movable sear controlling slide and serving when the slide is in its rearward position to cause the said sear to disengage the breech mechanism,-means for causing the slide to be moved forward in unison with the breech mechanism, means independent of the breech mechanism for moving the slide rearward immediately after its said forward movement, means for retarding the rearward movement of the slide so that there is a predetermined interval ment thereof effected by the slide, and a single manually operable means for moving the scar to a disengaging position and'for moving the said sear controlling slide to its forward position.

14. In combination in an automatic firearm, breech mechanism automatically movable rearward upon firing and biased for automatic return movement to its forward position, firing means automatically operable. when the breech mechanismreaches its forward position, a sear biased toward a position for engaging the breech mechanism to hold it in its rearward position, mechanism including a longitudinally movable sear controlling slide and serving when the slide is in its rearward position to cause the said sear to dis- K engage the breech mechanism, means for causing the slide to be moved forward in unison with the breech mechanism, means independent of the breech mechanism for moving the slide rearward immediately after its said forward movement, means for retarding the rearward movement of the slide so that there is a predetermined interval between the automatic engagement of the sear with the breech mechanism and the disengagement thereof effected by the slide, anda manually operable longitudinally movable slide serving when moved forward to engage the sear controlling slide to move it forward and also to engage the Sear to move it to a disengaging position.

15. In combination in an automatic firearm, breech mechanism automatically movable rearward upon firing and biased for automatic return movement to its forward position, firing means automatically operable when the breech mechanism reaches its forward position, a main sear and an auxiliary Sear each biased toward a position for engaging the breech mechanism to hold it in its rearward position, a manually operable trigger for moving the main sear to its disengaging posi` tion, mechanism including a longitudinally movable slide and serving when the slide is in its rearward position to cause the said auxiliary sear to disengage the breech mechanism, means for causing the slide to be moved forward in unison with the breech mechanism, means independent of the breech mechanism for moving the slide rearward immediately after its said forward movement, and means for retarding the rearward movement of the slide so that there is a predetermined interval between the automatic engagement of the auxiliary sear with the breech mechanism and the disengagement thereof effected by the slide.

16. Sear and trigger mechanism comprising in combination a sear biased to operative position, a trigger engageable with the sear to move the latter to inoperative position, and a sear retainer engageable with the sear to hold the same in its inoperative position and also being engageable by the trigger upon movement of the latter toward non-firing position to be moved thereby to a sear releasing position, the trigger being ,/movable to a predetermined extent before it moves the sear retainer to -sear releasing position thereby permitting the sear to move with a snap action free from restraint by the trigger upon disengagement of the sear and sear retainer.

17. Sear and trigger mechanism comprising in combination a sear biased to operative position, a trigger engageable with the sear to move the latter to inoperative position, and a pivoted sear retainer engageable with the sear to hold the same in its inoperative position and having a cam surface engageable by the trigger upon movement of the latter towards itsnon-flring position to be moved thereby to a sear releasing position, the

trigger being movable to a predetermined extent v' before it moves the sear retainer to sear releasing position thereby permitting the sear to move with a snap action free lfrom restraint by the trigger upon disengagement ,of the sear and sear retainer.

18. Sear and trigger mechanism comprisingin combination a sear biased to operative position, means including altrigger operable to move the sear to its inoperative position, and additional means including a searretainer engageable with \"the sear to hold the same in its inoperative position and also being engageable by said first mentioned means upon movement of the same toward non-firing position to be moved thereby to a sear releasing position, the trigger being movable to a predetermined extent before movement of the sear retainer to sear releasing position is effected thereby permitting the sear to move with a snap action free from restraint by the trigger upon disengagement of the sear and sear retainer.

19. In an automatic firearm, the combination of breech mechanim automatically movable rearward upon firing and biased for automatic return movement to its forward position, firing means automatically operable when the breech mechanism reaches its forward position, a sear biased toward a position for engaging the breech mechanism to hold it in its rearward position, a trigger for moving the sear to disengage it from the breech mechanism, a sear retainer biased to a position in which it holds the sear in its disengaged position, and means associated with the-Sear retainer and the trigger for automatically moving the retainer so as to release the sear and permit `it to move with a snap action -to its engaging positurn movement to its forward position, firing means automatically operable when the breech mechanism reaches its forward position, a sear in the casing adjacent the rear plate and biased upward toward a position for engaging the breech mechanism to hold it inits rearward position, a trigger on the rear plate for moving the sear downward to disengage it from the breech mechanism, a sear retainer biased to a position in which it holds the sear in its lower disengaged position, means associated with the sear retainer and the trigger for automatically moving the retainer so as to release the sear and permit it to move upward with a snap action to its engaging position when the trigger is returned upward to its non-firing position, and cam means associated with the sear retainer and the trigger for moving the retainer laterally out of the path of the trigger when the rear plate and trigger are moved downward during replacement.

MARRINER A. BROWNING.