US2384854A

US2384854A - Firing rate reducer

Info

Publication number: US2384854A
Application number: US473299A
Authority: US
Inventors: Clarence E Simpson
Original assignee: Individual
Current assignee: Individual
Priority date: 1943-01-23
Filing date: 1943-01-23
Publication date: 1945-09-18
Anticipated expiration: 1962-09-18

Description

Sept. 18, 1945. C, E, slMpsoN FIRING RATE REDUCER Filed Jan. 2s', 1943 @adm/Wham Patented Sept. 18, 1945 l f i Unirse STATES TENT ort-ics FIBING RATE REDUCEB. Clarence Simpson, Springfield, Mass.

Application January 23, 1943, SerialNo. 473,299

i ciaims. (ci. sc zr) (Granted under the act of March eglises, as i amended April 30, 1928; `370 O. G. 757) The invention described herein may be manufactured and used by or for the Government for governmental purposes, Without the payment to me of any royalty thereon.

This invention relates to automatic iirearms, particularly toa firing rate reducing mechanism -for such automatic rearms.

The firing rate of any particular automatic weapon can be said to be largely determined by the mass of the moving breech parts, the length of movement thereof, the energy absorption characteristics of `any buffer provided to stop such movement of the breech parts and, of course, the amount of energy imparted to the moving breech partsfby the discharge ,of a cartridge. 'Ihese determining factors' are relatively independent of any particular 'method of securing automatic operation, whether the rearin be of the'gas operated, blowbacl/ or recoil type. It will be noted' that none of these determining factors is capable of convenient adjustment to thereby'effect a variation in thefiring rate.' Furthermore, the stringent'weight requirements set up for modern military automatic firearms tend to produce a very high firing rate; This high firing rate is generally Vmuch above the ring rate which would permit extended or continuousring of the automaticweapon, due not only to excessive heating oi thehbarrel of the rearm, vbut also the effect of the rapid ring upon accuracy of the weapon. Thislatt'er disadvantage is particularly apparent in automatic shoulder weapons in which there is a considerable tendency of the muzzle end of the barrel lto raise upward or "clmb during automatic iring. Since many military situations require extended automatic iiring it is essential that the ring rate of an automatic firearm be capable of substantial reduction so as to permit extended automatic nring Without excessive heating and still not sacrifice any of the other desirable characteristics of the Weapon.

rate reducingl mechanisms have heretoforeb-een devised for such purpose but such prior designs have accomplished ring rate reduction only at the expense of sacricing other desirable military characteristics of the particular rearin such as elimination of semi-automatic ring, substantial increase in Weight or a weakening of the stock by iring rate reducing mechanisms inserted therein. i

Accordingly vit is an object of this invention to produceV an improved r-ing rate reducing mechanism -for rearms of the automatic type. Itis a Afurther object of this invention to produce .a firing -rate reducing mechanism which does not affect the semi-automatic'iiring properties of the automatic firearm.

lAnother objectof this invention is to provide a ring rate reducing mechanism which maybe entirely contained within a trigger guard group of the rearm and which does not substantially increase theweight of such firearm. l

It is a particular object of this invention to accomplish firing rate reductionof an automatic rearm by a method involving three distinct stops' of the moving Vbolt parts during the breech'opening-and closing part of the operation cycle of the automatic firearm. v

rIfhe specific nature of the invention as well as other objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawing in which:

Fig. 1 is a longitudinal sectional view of a trigger guard showing the arrangement of the firing rate reducing mechanism and related sear release mechanism. kAlso shown in longitudinal section is a breech member with sear in engagement with a sear notchin the breech member.

Fig. 2 is a partial perspective view of the top portion -of the trigger' guard-shown in Fig. 1. Fig.V 3 is a perspective YView of the carrier.

Fig. 4 `is a lperspective view of the Sear spring.` Fig. 5 is a lfront elevational View of the change lever. i Y

Fig. 6 is a cross sectional view of the change lever taken along theplaneG-KB of Fig. 5.V

Fig. 7 is aV cross sectional View ofthe change lever taken along the vplaine YI--l of Fig. 5.

Fig. 8 is a side elevational view of the connector with the web of the carrier shown in engagement therewith;

Fig. 9 is a perspective View ofthe depresser pin. Fig. 1051s a `fragmentary longitudinal sectional view showing an alternative modification of the firing rate reducing mechanism shown in Fig. 1. Fig. 1l is a top elevational'view of a spring utilized-vin theconstructionshown in Fig. 10.

The three-stop method of securing tiring rate reductionis illustrated in; two preferred embodimrls WhiQb :Will be `described in detail. The methodcan also be 'described generally, inde,- pendentv of Aany particuiar iirearin construction except that .the existence of a Y reciprocating breech member in the automatic iirearinv shall be assumed`- Upon discharge of the cartridge from such firearm, the breech member is unlocked and moves rapidly to the rear under the iniiuence of a force derived in any desired manner from the discharge of the cartridge. The

first stop of such reciprocating breech member is caused by the breech member striking a buffer or otherwise reaching the end of its rearward movement in the usual manner. Under the inuence of the buffer recoil force and the compressed operating spring, the breech member then reverses its direction and starts forward to its battery position. In accordance with this invention, at some point in this forward movement of the breech member, the breech member engages a sear and is brought to the second stop by the sear. The sear is mounted for limited reciprocal movement in a plane parallel to the axis of the breech member and a strong spring opposes any forward movement of the sear and hence is compressed by the force exerted on the sear when the breech member strikes the sear and is stopped thereby. This sear spring is sufficiently strong to move both the sear and the breech member engaged therewith rearwardly against the bias of the operating spring. Near the' end of this limited rearward movement the searvis tripped out of engagement with the breech member. The breech member is then under the sole influence of the operating spring which stops the rearward movement of the breech member, making the third stop, and then .drives the breech member forward to its battery position. 'The extraction and ejection of the discharged cartridge is accomplished on the initial rearward l movement of the breech member by a conventional mechanism while the loading of the next cartridge may be conventionally accomplished either on the initial or final forward movement of the breech member. This three-stop method naturally results in a reduction in the ring rate of the automatic weapon due to the delay inherent in the repeated stopping and reversing of the movement of the reciprocating breech member.

From th'e preceding general description of the three-stop method of securing firing rate reduction, it is apparent that the method is independent of any particular type of automatic firearm construction so long as a reciprocating breech member is included. Therefore the following description of two preferred embodiments of Ythis invention as applied to an automatic firearm of the type disclosed in U. S. Patent No. 1,293,022 to John M. Browning should not be construed as limiting the scope of this invention to that particular type of firearm.

In Fig, l there is shown in assembled relation, a portion of the elements of an automatic firearm generally of the type disclosed in U. S. Patent No. 1,293,022 to John M. Browning. The portion shown comprises a trigger guard frame I which is provided with a pistol grip portion Ip. This trigger guard frame is supported by the receiver and stock of the rearm (not shown) in its conventional relation therewith and underlies a breech member 2 which is conventionally mounted in the receiver for sliding reciprocal movement therein.

The top of the trigger guard frame I is provided with two sets of vertical extensions la and Ib on each side oi' the frame I defining a channel lc between such extensions. A long rectangularly-shaped carrier member 3 is mounted for limited reciprocal movement within the channel Ic. 'I'he rear end of the carrier 3 is bifurcated in two portions 3a and 3b. The central portion 3h of the carrier 3 is hollow except for a transverse member 3c which extends across the hollow` portion 3h for a purpose that will be described later. At the forward end of the hollow portion 3h the walls of the carrier 3 have opposed slots 3d and 3e formed in the walls. The extreme forward portion of the carrier 3 defines a cylindrical open chamber 3f. When the carrier member 3 is mounted within the channel Ic the chamber 3f acts as aV spring seat for a spring 4. The other end of the spring 4 is supported by a spring seat In provided in the trigger frame-and a guide pin 5 is secured to the base of the spring seat in and projects into the turns of the spring 4.

In the forward opposed frame extensions Ib holes Ie are provided in which' a pin 6 is inserted, the pin 6 also traversing the slots 3d and 3e of the carrier 3. The rear opposed frame extensions Ia are slotted as shown at Id and a pin 1 passes through these slots and engages the holes 3p and 3ir in the carrier 3. Thus reciprocal movement of the carrier 3 within the channel Ic is limited by the length of the slots ld, 3d and 3e.

A T-shaped sear 8 is provided. This sear closely resembles the conventional sear but is provided with a greatly increased length of depending foot portion 8a. In the central portion of thesear a hole 8e is provided and the sear is secured to the trigger guard assembly by the engagement of the hole 8e by the pin 1, the foot portion of the sear projecting down between the portions 3a and 3b of the carrier 3. Limited pivotal movement of the sear about the pin 'I is therefore permitted without interference with the carrier 3. The rear end of the sear 8 is provided with a contact surface 8b which when the sear is pivoted slightly counterclockwise as viewed in Fig. 1 projects into the path of a correspondingly shaped latching surface 2c of the breech member 2 and thereby locks the breech member 2 against any further forward movement of the breech member. The latching surface 2c is the rear wall of a recess 2a in the bottom of the breech member.

Pivotal movement of the sear is accomplished by a trigger arrangement very similar to that disclosed in U. S. Patent No. 1,293,022 to John M. Browning. The trigger 9 is provided with a forwardly extending portion 9a, in which is located the trigger pivot hole 9b. The trigger is secured in position in the trigger frame by engagement of the hole 9b by the pin 6. The forwardly extending portion Qa of the trigger fits into the hollow portion 3h of the carrier 3, entering that portion which is forward of the transverse member 3c. Immediately above the finger engaging portion of the trigger 9, there is a bifurcated trigger extension Sc and projecting across the central portion of the bifurcated extension 9c is a pin 9d suitably secured in each of the bifurcated portions. A connector I0 of conventional shape is supported by the pin Sd engaging a suitably shaped recess Illa in the base of the connector.

The actual direction of movement of the connector IEI when the trigger 9 is pulled is con-Y trolled by a conventional change lever II. The change lever II essentially comprise a transverse pin mounted in the trigger guard frame I and provided on its exterior ends with an operating handle Ila. The change lever II is arranged to lie in the path of an arcuate surface I0c of the connector I0 when the connector is raised by operation of the trigger. The change lever Il may be rotated to three distinct positions and in each position a different type of camming action is exerted on the arcuate surface Ic of the` connector I0. AIn place of theflat leaf spring usually provided to yieldinelv hold. the ,Change lever l! any of k,its three positions,V a detect g shrouded for this purpose.A A',Ihe detect. If/2 `.commises a relatively long partly hollow cylin- .diical portion 12o which is loosely litted in ,a vertical .hole lo provided in the .tries-er guard .frange i, Titeldaten-.t ,arm 12b is secured to the teo of the cylindrical portion 12o and at right angles :thereto and proiects over 4,the change lever ii, detect arm lb is provided with a 4depending tooth .I2C which may engage any one of three adjacent teeth .llc provided o n the change lever II.' The detent i2 is resiliently biased into engagement with .the teeth IIc bythe force of Y a spring .I3 @which is mounted within the `hololow Aportion of the detent I2 and compressed therein by a pin i4 also mounted within `the same hollow portion and lon top of the spring iS. f'lhe' spring I3 is Vcompressed by engage ment' of the top of the pin I4 with -a :transverse web portion 3j provided inthe carrier 3. Hence the change lever AII is resilientl-y held inposition,V as show-nin Fig. l, vbut may be forcibly rotated lin a clockwise direction into two additional positions, the teeth IIc acting to cam the' detent I2 lupwardly to permit the rotation. Further rotational movement of the change lever i i beyond the Ythree positions defined Iby the teeth Iic is prevented by suitable `stops on the change lever which are not shown. In the position of the change lever II shown in Fig. 1, a lrecess IId in the body of the lever is positioned directly above the yarcuate surface IgIlc of the connector I3, Hence in this position of the change lever gI, actuation of the trigger 9 will move the connector I9 directly upward without any interference being exerted b y the `change lever II as the arcuate surface Il )c enters the recess IId. By such'moyement the top surface 10b of the connector I is brought into engagement with the bottom Isurface of the forward end of the sear 8 and thus the sear 8 is pivoted slightly clockwise to effect the release of the breech member 2,

It should be mentioned that a Conventional @at spring I5 is provided to bias the sear into its cocked position. One end I5a of the spring I5 is secured within the carrier 3 by being in` serted in opposed grooves V3g provided in the re Walls at the end of carrier 3. The other end of spring I5 comprises a three-pronged fork portion, 4the two exterior ngers I5b are parallel While the VVcentral forked portion I5c projects slightly below the surface of the .other two forks. rlhe two forks I5b engage the top surface of the front end of the Sear 8 exerting a force thereoli Which biases the sear in a counterclockwise direction. The central linger I5c engages a sloped surface I Ue on thetop of the connector In and thereby exerts a .Constant bias on the connector I8 tending to pivot it in a clockwise direction on the pin 9d.

Clockwise pivotal movement of the connector l0 is prevented by engagement of a rear vertical surface IIlj provided on the top of the connector I0 with the forward end of the web 3i of the carrier 3. The connector II) lis supported on its front side `by a .Small projection 3m integrally formed on the inner wall of the carrier This projection engages a shoulder IDg on the adjacent side of connector IU. Immediately adjacent to and below the vertical surface Illf there is provided a sloped cam surface Ih on the-connector I0. Upon actuation ofthe trigger this surface engages a correspondingly shaped undersurface 37c of the web 3g' and the comming actionbetween such surfaces .made to pivot the connector :IB counterclockwise and moves :the top of the. connector forward against the bias of the middle finger I 5c .of the spring fork. The connector Ill is guided in this movement by the projection 3m against which the shoulder I 0g of the .connector slidably bears. This movement .of Ithe connector IzIl is of sufiicient extent to move the top soar engaging surface -I 0b of the connector out from .under the forward end of the sear 8 and hence permits the 'scar to Asnap back to its normal position under ythe bias Vof the spring fork iingers |1512. VThis produces semiautomatic ring of the firearm as actuation of the trigger rst releases the scar from cocked en.- gagement with the breech member and then re,- turns the sear to its breech member .engaging .or cocked position. `II'hus the trigger must be ref leased and pulled again to re the next round. When the change lever I I is rotated clockwise to its next position, a projecting `small shoulder I-Ie along the base of the walls defining the recess IId of the change lever II is thereby rotated in .the proximity of theend of the arcuate surface Illc of connector I0. In this position the actuation of the trigger 9 will again raise the connector Il) agnd the arcuate surface Ic enters into the recess IId of change lever I I; however, the interaction of the cam surface I8h and the corresponding surface 31C on the web 37' will not produce a movement ofthe connector I0 out of engagement with the sear 8 for the end of arcuate surface Inc now strikes the shoulder IIe preventing further movement of the connector I0. Therefore in this position of the change lever the scar 8 remains pivoted and disengaged from the breech member as long as the trigger is pulled and hence this condition produces automatic operation of the firearm.

Rotation of change lever II to its third and 40 final position brings a solid portion of the change lever into the path of the arcuate surface IIJc of the connector IU and therefore stops the upward movement of the connector `Il) due to actuation of the trigger before the connector can move a suicient distance to rotate the scar out of latched engagement with the breech member. Hence this position of change lever .II constitutes the safety position of the firearm.

A recess I r is provided in the trigger frame I immediately below the pin 'I and the foot 8a of the scar extends into this recess. This 'foot 8a has a projecting heel 8c on the forward end of its base, the heel projecting a substantial distance beyond the remainder of the base 8d of the sear foot 8a. In the bottom of the recess Ir, a hole Ih is provided into which a bolt-like plunger member I6 is inserted. This plunger I6 is resiliently biased upward by a spring I 1 in the bottom of the hole Ih. The top of the plunger I6 normally abuts against the base of the heel 8c of the scar foot 8a. A depressor pin I8 is mounted within the trigger frame I to latch the plunger I6 out of engagement with the heel 8c. The member I8 comprises a transversepin extending through thetrigger frame I and provided on its exposed extremity with an interior socket head I 8c so that itmightbe rotated by insertion of a suitable tool or the nose of a bullet. A flange I8b is provided in the center of the depressor pin I8 and this angeserves to secure the depressor latch in its proper position in the trigger frame I when the woodenside 'pieces I9 are fastened to each sideof the pistol grip Ip of the trigger frame as by the screws Illa. A portion of the depressor I projects rntorthe hole I h inwhich the plungerV ,I6

is located. A clearance cut IIa is provided -in the plunger I8 to accommodate the Projecting portion of the depressor I8. A clearance cut 18a is provided in the depressor I8. This cut I8a permits the plunger I6 to move freely in the hole Ih, when the depressor is in the position shown in Fig. 1. If however the depressor pin I8 is rotated 90 clockwise from the position shown in Fig. 1, then a solid portion of the 'depressor pin will. extend into the hole Ih, entering the recess I6a in the plunger I6. Further rotation ofthe depressor pin I 8 will engage the base of the clearance cut Illa with the base of the clearance cut IIa of the plunger I6 and force the plunger I6 downward and hence out of engagement with the heel 8c of the Sear foot 8a. The friction exerted upon the flange Ib of the depressor pin by the wooden side pieces I9 will be sufficient to maintain this position and hence the plunger I8 is effectively latched out of engagement with the sear 8 whenever the depressor pin I8 is rotated clock- W1se.

The transverse member 3c extending across the hollow portion of the carrier 3 has already been mentioned. A horizontal rearward projection 9e is provided in the top of the trigger 9. The position of this projection is such that in the inactuated position ofthe trigger the projection 9e lies directly yin the path of frontalmovement of the transverse member 3c and hence frontal movement of the carrier is prevented. However when the trigger is actuated, the projection 9e is raised above the transverse member 3c and the transverse member can move freely within a recess S directly below the projection Se in the trigger 9. Thus no limitation is placed on the movement of the carrier 3 when thetrigger 9 is maintained in its actuated position.

Before `proceeding with the description of the various modes of operation of this improved construction, it is desired to emphasize again that any conventional ibolt 4action and methods of extraction, ejection, and feeding of cartridges may be utilized so long as there is provided a reciprocating breech member which may be engaged by the sear 8 and firing of the weapon thus prevented until the sear 8 is released from engagement therewith.

Full automatic `operation without ratered'uctz'on Despite the several changes in construction as evident from the foregoing description, the operation of this improved mechanism-under full automatic re without rate reduction is essentially the same as the operation of the firearm disclosed in U. S. Patent No..1,293,022 to John M. Browning. The change lever IIjis set in its central position. Assuming that a cartridge is in the magazine of a rearm and the breech member 2 has been retracted to its cocked position wherein the sear 8 engages the latching surface 2c of the breech member, the actuation of the trigger 9 raises the connector I0 in substantially a vertical path, hence raising the front end of the sear 8 and tripping Ythe rear end of the sear out of engagement with the breech member. The breech member therefore drives forward under the force of the compressed operating spring (not shown) picking up the cartridge from ythe magazine and loading and firing the-cartridge in the conventional manner. A force from the resulting explosion is applied to the breech member driving it rapidly rearward. Since the shoulder IIe in the recess IId of the change lever IIv is abutting against the end of the arcuate-surface,

Illc of the connector Ill, counterclockwise pivotal movement of the connector due to camming action of surfaces IIlh and 3k: is prevented and hence the connector I8 remains in engagement with the frontI end of the sear 8. Therefore as long as the trigger is maintained in the pulled position,the rear end of the sear 8 remains out of the 'path of the breech member 2 and the weapon continues to re automatically at its natural rate since the breech member 2 reciprocates freely without delay of any sort being introduced.

Semi-automatic without rate reduction It is likewise possible to secure normal semiautomatic operation with the construction described. To obtain this type of operation, the change lever Il is rotated counterclockwise to its extreme position. The depressor pin I8 is rotated clockwise to latch the plunger I8 out of engagement with the sear foot 8a. Then after retraction and cooking of the breech member 2, the actuation of the trigger 9 raises the connector I0 in a vertical path hence tripping the sear 8 out of engagement with the breech member 2. However, the connector I0 is pivoted counterclockwise by the co-action of its surface IIlh with the web surface 37 and moved out of engagement With the front end of the sear 8. Hence the sear 8 immediately returns to the cocked position due to the .bias of the spring fingers I5b. On the recoil stroke of the breech member 2 following the discharge of the cartridge, the bottom breech member surface 2b rides over the rear end of the Sear 8. `The sear is entirely free to pivot counterclockwise a slight amount against the bias of the spring forks v|51) to permit the passage of breech member 2. As soon as the recess 2a in the breech member 2 becomes adjacent to the rear end of the sear 8, the sear pivots back to its cocked position under the influence of its spring forks I5b and thus latches the breech member against forward movement under the influence of the compressed operating spring. Regardless of whether the trigger has been maintained pulled or released, it is therefore necessary to actuate the trigger again to effect the discharge of the second cartridge.

Full automatic fire at full reduced rate To secure reduced rate, full automatic fire, the change lever II is left in the same position as uitilized in securing normal rate semi-automatic `fire. The depressor pin I8 however is rotated counterclockwise to release the plunger I6 and permit it to resiliently engage the heel 3c of the sear'foot 8a under the influence of the spring I'I. With the components set as described and, as usual, assuming that the magazine is loaded with cartridges and that the breech member 2 has been manually retracted to its cocked position with sear surface 8b in engagement with breech member latching surface 2c, the weapon may be fired automatically at a reduced rate by pulling the trigger and the connector Ill in this instance is exactly the same as already described in the semi-automatic operation, i` e., the connector I0 raises the front end of the sear 8 hence tripping the rear end of the sear out of engagement with the breech member 2 and permitting the breech member to drive forward to load and re the cartridge. The connector Ill at the same time is cammed out of engagement with the front end of the scar 8 permitting the sear to return to the cocked position under the influence of spring finger |511. The connector I0 remains in this position, independent of the sear 8, so long as the mal automatic and semi-automatic fire is identical to that described for the previous modification with the only exception being that instead of operating the depressor pin to secure semi-automatic operation, it is necessary in this modification to fasten down spring portion 2llb by means of the screw 2| in the manner described.

To secure automatic operation with reduced firing rate, the screw 2l is turned to release spring portion Zb. The spring portion 2Gb thus yieldingly engages the bottom of the heel 32 of the sear foot 3 l. Then' upon pulling the trigger 9 and holding the trigger pulled, the same cycle of operations as described in the previous modification occurs, namely, the sear pivots, unlatching theV breech member and permitting the breech member to drive forward to load and nre the cartridge. At the same time the connector I moves out from under the sear 30 permitting the sear to return to its cocked position under the inuence of spring forks |512. The breech member flies back on its recoil movement overriding the rear end of sear 30, strikes a buffer and starts forward under the influence of the compressed operating spring when it is stopped by engagement with the rear end of the sear 30, The impact of the breech member 2 upon the sear 30 is transmitted through the pin 'l to the carrier 3. The carrier moves forward compressing the spring 4 until the carrier is stopped by engagement of its forward end with its spring seat I f. The forward movement of the carrier of course moves the sear 30 forward and the heel 32 moves.

forward over the end of the spring portion h and that spring portion now engages the sloped base 33 of the sear foot 3l. The compressed carrier lspring then moves the carrier 3, the sear 30, and the breech member 2 latched therewith rearward against the force of the compressed operating spring, thus producing the second stop and reversal of movement of the breech member 2.l .Such rearward movement brings the rear .end of the heel 32 into engagement with the forward end of the spring portion Zlib. This engagement results in a counterclockwise pivoting of the sear 30. Such pivoting drops the rear end of the sear out of engagement with the breech member 2. The breech member 2 is thus under the sole influence of the compressed operating spring which stops and reverses its rearward movement and drives it forward to load and fire the next cartridge. Hence thethird stop and reversal of direction of the breech member 2 is accomplished.

The completion of the rearward movement of the carrier 3 drags the heel 32 of thesear foot 3l up over vthe end of the spring portion 20h, permitting the sear `30 to return to its cocked position under the influence of spring forks 15b. The elements are thus restored to their initial position ready for another cycle of automatic firing.

The second described modification of course utilizes the same three-stop principle as does the rst modification. It is particularly recommended wherever the requirements of the particular weapon do not permit the use of a pistol grip and where there'is no requirement that the means for changing from full automatic nre to reduced rate automatic nre and vice versa shall be readily available without disassembly of the weapon I claim:

1. In an automatic rearm having a receiver and a reciprocating breech member, a sear arranged to engage the breech member on its forward stroke, means mounting said sear to said receiver permitting limited linear movement of the sear with respect to the receiver; resilient means arrangedto be stressed by forward linear movement of the sear under impact of the breech member engagement and means engageable by said sear on rearward movement thereof under the biasof said resilient means for disengaging said sear from said breech member.

2. In an automatic rearm having a receiver and a reciprocatingv breech membena sear arranged to pivot into engagement with the breech member on its forward stroke, .a spring biasing said searinto a breech member engaging position, means mounting said sear to said .receiver permitting limited linear movement of thefsear with respectto the-receiver; resilient means arranged to be stressed by forward linear =move mentv ofthe sear under impact of the breech member engagement and means engageable by said sear on rearward movement thereof under the bias of said-resilient means for disengaging said sear from said breech member.

3.1 In an automatic firearm having a receiver and a reciprocating breechmember, a sear arranged to pivot into engagement with the breech member on its forward stroke, a springbiasing said searv into a breechy member engaging posi-` tion, Vmeans mounting.. said searto said receiver permitting limited-linear movement of the sear with respect to the receiver; resilient means arranged to be stressed byf forward linear. .move-v ment .of thesear under impact of the breech member engagement, an extension on' said searl and a spring biased member arranged to beengaged by said sear extension to pivot said sear out of breech member engagement bythe` rearward movement of the sear under the bias of said resilient means. l -f 4. In an automatic nream having a-receiver and a reciprocating breech member, a sear arranged to engage the breech member onits-forward stroke, means mountingsaid sear toasaid receiver permitting limited linear movement of the sear withrespect to the` receiver; resilient means arranged to be stressedby -forward linear movement of the sear under impact of the-breech member engagement, Vmeans engageable bysaid sear on rearwardmovement thereofV under thev bias of said resilient means-for disengaging saidy searfrom said breech member, and manually operated means arranged to render said. precedingmeans inoperative. v .1

5. In an automatic iirearm having a receiver and a reciprocating breech member, a sear arranged to pivot into engagement with the breech member on its forward stroke, alspring biasing said sear into a breech member engaging position, means mounting said sear to `said receiver permitting limited linear movement of the sear with Yanda reciprocating breech membena sear car-V rier mounted on said receiver for limited linear movement, ay spring arranged to bestressed'by forward movement of said carrier with respect to the receiver, a sear pivotally mounted on said carrier and arranged-to engage the breech mem` trigger is maint-dined in the pulledpositioii. on 'the recoil strokeoi the breech hierdoor' 2, the rear ebd' of the segr is depressed by theloottorri sdr-l i'eoe 2o of the bre-ech riieriiber 2 and their under the influence of the spring riger's leb the secr s pivots its rear er'ld i'litothe e'cessv Za Where' the' scar surface 8b`r`lgag's' the ltchgllrfetce 2c of tlie breech member es the breech member begins its rtn movint: t s'ho'llld be llder'stood that any" desired biiiiir'jig mecbdriisiii ceri ibe ose-d to stop and reverse the recoil movement of the oieech merriber. Such buffer stopY constitutes the' dist stop epd reversal of' direction of the breech member. The secoiid 'stop-of the breech iiieiriberv lS brouglltabt as described by the lo'lie'dcl'iA lnerr'l- 2 s'tr'ik'iiig the seer 8. A The force of this irripect is transmitted through the secr s erid the pin 1 tothe terrier 3* arid the carrier starts to move forti/ord onder iriipttct. The forward rhoifedreht of the oei'r'rierv compresses the carrier spriiig 4 and is stopped by' ligggrineilt f the frontal d f th' caiil': 3 Witl th Spring' Yscat This dioveiiient is siriiioienttol slide the heel 8c `oi the seer foot ad,- off the top of tlie pluiiger it and the plunger lo' oir' cotr'rse risesiirider tire influence :s f' spring '1" to o higher position where it engages bose portieri ad of the secr' footl 8c. As already creiitioried the vcer'r'ier' sprjirig is edite strong and ih foots'iifiicieiitly strorigto ipovetlie carrier', secr ifid breech member' 2* lettcliedv thereto, rearward matic firing ait' a, substantially; rdl'' falte ixly of tliechcriiiel le. H

The cehtrol section' of spring' portion 2nd is provided with e longitudinal' slot id. A threadeed hole im is provided iri the base of the recess tj u'riiderlyiog the slot 2nd iii spring porti-ori ao. A screw 2l is threaded loto hole im. "l'r'hisscrewI zi' e lorig narrow' heed which wheri dligped with the slot zfiid will pessthrodgh the slot. 'fhiis by depressing sprirlg portieri 20o arid permitting heed zld of the screw 21| to project through the slot 2cd, the spring' portion i615 coin` be securely' lield d'owri' parallel to the base of the channel lo by turn-ing the screw 2| to e position where the heed 2li-o' is et rightl ongles to the exisI ofthe slot 20d. The s'eai 30 utilized r'l this moi'oatioiiv is in general similar to the secr already des'cri ed the previous modification witl'i thev excpti' llovif'elr that the Solar foot is getly re'diiced ifi length. This of coursejwis iie'oess'ary sii-ice this' modiiicetior'i does not utilizey o recess ldlath tle s'tziry sll'lclas provided iii the pistol gripv portion it of trigger treme of. Fig. 1'. This seat 30 ho'vl'fvcr has forward' and le'al ends slaild identically to the Sear of Fig; which co"- operate with the connector l0 and theY b`r''ech lel'lllcei" latch surface' 2c' respectivel'yiri the same rrieririer es iii the previous modification. The secrl foot ell also has the som-e projecting heel 3'2 ber on its forward stroke thereby moving said sear carrier forwardly, a; spring pivotally biasing the Sear into its breech member engaging position and means engageabl'e by said sear on the rearward movement of said scar carrier under the bias of Asaid first mentioned spring for disengaging said' sear from the breech member.

'7. In an automatic rearm having a receiver' and a reciprocating breech member, a sear arranged to engage the breech member' on its frward stroke, means mounting said Sear to said receiver permitting limited linear movement of the sea'r with respect to the' receiver; resilient means arrangedY to be stressedv by forward linear movement of the sear under impact of the breech Y member engagement, means'V disengaginfg said' Sear from the breech member by the rearward movement of said se'ar under the bias of saidl re'- silient means, trigger means efiective to initially release the sear from the breech member and a stop actuated by release of said trigger means to.

engage said sear mounting means to limit the forward linear movement of said Sear.

8. In an automatic firearm having a receiver and a reciprocating breech member, a scar arranged to pivot into engagement with the breech member on its forward stroke, a spring biasing said Sear into abreech member engaging position, means mounting said scar to said receiver permitting limited linear movement of the sear with respect to the receiver; resilient means arranged to b'e stressed by forward linear movement of the sear under impact of the breech member engagement, an extension on said sear, a spring biased member arranged to be engaged by said sear extension to pivot said sear out of breech member engagement by the rearward movement of the sear under the bias of said resilient means, trigger means effective to initially release the sear from the breech member and a stop actuated by release of said trigger means to engage said sear mounting means to limit forward linear movement of said sear.

9. In an automatic firearm having a receiver and a reciprocating breech member, a sear arranged t engage the breech member on its forward stroke, means mounting said sear to said receiver permitting limited linear movement of the sear with respect to the receiver; resilient means arranged to b'e stressed by forward linear movement of the sear under impact of the breech member engagement, means disengaging said sear from the breech member by the rearward movement of said sear under the bias of said resilient means, manually operated means arranged to render said preceding means inoperative, trigger means effective to initially release the scar from the breech member and a stop actuated by release of said trigger means to engage said sear mounting means to limit forward linear movement of said sear.

10. In an automatic firearm having a receiver and a reciprocating breech member, a sear arranged to pivot into engagement with the breech member on its forward stroke, a spring biasing said sear into a breech member engaging position, means mounting said sear to said receiver permitting limited linear movement of the Sear with respect to the receiver; resilient means arranged to be stressed by forward linear movement of the scar under impact of the breech member engagement, an extension on said sear, a spring biased member arranged to be engaged by said sear extension to pivot said sear out of breech member engagement by the rearward movement of the sear under the bias of said resilient means, manually operated means arranged to render said? spring biased member inoperative, trigger means eiieeti've to initially release the Sear from the breech member and a stop actuated by release of said trigger means to engage said sear mounting meansA to limitv forward lineary movement ofV said scar. Y y

il. In an automatic" firearm having a receiver a "d a reciprocatingbreech member', a scar carmounted on saidr receiver for limited linear movement, a spring arranged to be stressed by idrwar'd movement of said carrier Wi-th respectto' the receiver,- a Sear pivotally mounted on said carrier and arranged to engage the breech inem-- n from the breech member, trigger means effective to initially release the sear from the breech member, and a stop secured to said trigger means, said stop arranged to engage said sea-r carrier in the released position of said trigger means to limit forward movement of said carrier.

12. In an automatic firearm having a receiver and a reciprocating breech member, a sear carrier mounted on said receiver for limited forward movement, a spring arranged to be stressed by forward movement 0i said carrier with respect to the receiver, 'a sear having its central portion pivotally secured to said carrier, the rear end of said sear arranged to engage the breech member on its forwardrstroke, a spring pivo-tally biasing the sear into its breech member engaging position, semi-automatic trigger means engageable with the forward end of said sear to initially release the sear from the breech member, a depending sear portion, and a latch resiliently engaging said depending sear portion and effective during rearward movement of said scar and sear carrier under the biasof said first mentioned spring to pivot said sear out of breech member engagement.

13. In an automatic firearm having a receiver and a reciprocating breech member, a sear carrier mounted on said receiver for limited forward movement, a spring arranged to be stressed by forward movement of said carrier with respect to the receiver, a sear having its central portion pivotally secured to said carrier, the rear end of said sear arranged to engage the breech member on its forward stroke, a spring pivotally biasing the sear into its breech member engaging position, semi-automatic trigger means engageable with the forward end of said sear to initially release the sear from the breech member, a depending sear portion, a latch resiliently engaging said Idepending sear portion and eiectiveduring rearward movement of said sear and sear Carrier under the bias of said first mentioned spring to pivot said sear out of breech member engagement and manually operated means arranged to hold said latch out of engagement with said depending sear portion.

14. In an automatic firearm having a receiver and a reciprocating breech member, a scar carrier mounted on said receiver for limited linear movement, a spring arranged to be stressed by forward movement of said carrier with respect to the receiver, a sear having its central portion pivotally secured to said carrier, the rear end of said sear arranged to engage the breech member on its forward stroke, a spring pivotally bi asing the sear into its breech member engaging position, semi-automatic trigger means engageable with the forward end of said sear to initially release the sear from the breech member, a depending sear portion, a latch resiliently engaging said depending sear portion and effective during rearward movement of said sear and sear carrier under the bias of said first mentioned spring to pivot said Sear out of breech member engagement, and a stop secured to said trigger means and eiective in the released position of said trigger means to limit forward movement of said Sear carrier.

15. In an automatic firearm having a receiver and a reciprocating breech member, a sear carrier mounted on said receiver for limited linear movement, a spring arranged to be stressed lby forward movement of said carrier with respect rto the receiver, a sear having its central portion pivotally secured to said carrier, the rear end of said sear arranged to engage the breech member on its `forward stroke, a spring pivotally biasing the Sear into its breech member engaging loosn tion, semi-automatic trigger means engageable with the forward end of said sear'to initially release the sear from the breech member, a depending sear portion, a latch resiliently engaging said depending Sear portion and effective during rearward movement of said sear and sear carrier under the bias of said rst mentioned spring tolpivot said sear out of breech member engagement, a stop secured to said trigger means and effective in the released position of said trigger means to limit forward movement of Said sear carrier and manually operated means arranged to hold said latch out of engagement with said depending sear portion.

CLARENCE E. SIMPSON.