US2270408A - Cartridge-detent mechanism for repeating firearms - Google Patents

Description

F. F. BURTON Jan. zo, 1942.

CARTRIDGE-DETENT MECHANISM FOR REPEATING FIREARMS Filed April 13, 1959 3 Sheets-Shes? l @m w @s I m, fw W w ,f m l L@ hm mms. ..5 www @n mh .mm wkn wh b km ---l o -l` M.%\o r mm mw //-r.% .7/ l@ mil@ m s F. F. BURTON 2,270,408

CARTRIDGE-DETENT MECHANISM FOR REPEATING FIREARMS Filed April 13, 1939 3 Sheets-Shel??l 2 iff Jan. 20,1942. F F, BURTON V.2,270,408

CARTRIDGE-DETENT MECHANISM FOR REPEATING FIREARMS Filed April l5, 1959 3 Sheets-Sheet 3 Patented Jan. 20, 1942 naar CARTRIDGE-DETENT MECHANISM FOR REPEATING FIREAiRMS Frank F. Burton, Mount Carmel, Conn., assignor to Western Cartridge Company, New Haven, Conn., a corporation of Delaware Application April 13, 1939, Serial No. 267,531

Claims.

This invention relates to improvements in repeating or magazine firearms and more particularly to the cartridge-detent means for such firearms.

One of the objects of the present invention is to provide superior means for alternately detaining and then releasing successive cartridges as the same move from the magazine of a repeating firearm, to insure the one-by-one feeding of such cartridges into the cartridge-chamber of the firearm; the said means being characterized by simplicity and reliability.

Another object of the present invention is to provide superior means for the purpose just above described which may be alternately but positively moved into cartridge-detaining.position and into cartridge-releasing position as a result of the movements of the breech-bolt of the firearm.

A further object is to provide a superior cartridge-detent mechanism for repeating firearms, characterized by its freedom from mutilating effects upon the cartridges being controlled.

Still another object is to provide a superior cartridge-detent mechanism for repeating firearms Which will function to feed successive cartridges without occasioning the jamming of such cartridges or the jamming of the mechanism of the firearm.

A still further object is to provide a superior cartridge-detent mechanism for repeating firearms characterized by its non-dependence on springs, or the like, for its proper functioning.

Another object is to provide a repeating firearm with a superior cartridge-detent mechanism providing a maximum degree of surface area for engagement with the cartridges as the same are fed from a magazine, to thereby insure the reliable and effective functioning of the firearm.

With the above and other objects in View, as will appear to those skilled in the art from the present disclosure, this invention includes all features in the said disclosure which are novel over the prior art and which are not claimed in any separate application.

In the accompanying drawings, in which certain modes of carrying out the present invention are shown for illustrative purposes:

Fig. l is a broken view in central verticallongitudinal section of the mid-portion of a magazine or repeating firearm embodying the present invention,` the breech-bolt being shown in its breech-closing position and the firing-pin and associated mechanism being shown in the positions due to them an instant after the discharge of the firearm;

Fig. 2 is a similar but slightly less comprehensive view and showing the parts in the positions which they assume When the breech-bolt is in its fully retired position;

Fig. 3 is a view partly in side elevation and partly in vertical central-longitudinal section of the portion of the firearm shown in the preceding figures and showing the parts in the positions which they assume when the breech-bolt, in its forward travel, approaches its breech-closing position;

Fig. 4 is Ia broken View in transverse section taken on the line 4--4 of Fig. 1;

Fig. 5 is a similar view taken on the line 5-5 of Fig. 2;

Fig. 6 is a broken transverse-sectional view taken on the line 6 6 of Fig. 3;

Fig. 7 is a broken view in transverse section taken on the line 1-1 of Fig. 1;

Fig. 8 is a view in side elevation of the breechbolt stripped of the parts ordinarily organized therewith;

Fig. 9 is a view thereof in front-end elevation;

Fig. l0 is an underside view thereof;

Fig. 11 is a top or plan view of the magazinethroat unit;

Fig. 12 is a view thereof in side elevation;

Fig. 13 is a View of the magazine-throat unit on a larger scale than Figs. 11 and 12 and viewing the same from the direction indicated by the arrow A of Fig. 12; and

Fig. 14 is a perspective view of one of the complemental cartridge-control levers.

The particular repeating firearm herein chosen for the purpose of illustrating the present invention is of the automatic type, that is to say, it is a firearm of the type in which the discharge of one cartridge effects the extraction and ejection of the just-fired cartridge and the insertion of a fresh cartridge into the cartridge-chamber of the firearm. The present invention, however, is not limited to firearms of the automatic type but is applicable to various types of repeating firearms as will be apparent from the following.

The firearm shown comprises a stock 2li upon which is superimposed a receiver 2| and a barrel 22. The said barrel 22 is rigidly coupled to the forward end of the receiver 2l in any apapproved manner, such, for instance, as by threading the rear-terminal of the said barrel 22 into the internally-threaded forward end of a breech-bolt passage 23 extending axially throughout the length of the receiver 2|. The

barrel 22 is formed with the usual axial bore 24 having its rear portion slightly enlarged to provide a cartridge-chamber 25.

Mounted for reciprocating movement in the axial breech-bolt passage 23 in the receiver 2|, is a breech-bolt 25 which is yieldingly urged forwardly into its breech-closing position by a helical breech-bolt-return spring 21 pressing at its forward end against the said breech-bolt 26 and pressing at its rear end against a removable receiver-plug 28. The said receiver-plug 28 is removably installed within the rear end of the breech-bolt passage 23 in the receiver 2| in any approved manner not requiring detailed description herein such, for instance, as is more fully set forth in my co-pending application Ser. No. 233,941, filed October 8, 1938.

The receiver-plug 28 is formed in its side with a cavity 29 in which is adapted to reciprocate a limiting-finger 3U depending from the rear end of an action-slide 3| having its forward end secured b-y means of a pin 32 to the side of the rear portion of the reciprocating breech-bolt 26 as is shown in Figs. 1 and 2. As shown, the rear portion of the action-slide 3| is formed with an outwardly and upwardly-extending knurled ngerpiece 33 by means of which the breech-bolt 25 may be manually moved rearwardly.

Reciprocating in the upper portion of the breech-bolt 29 is a firing-plunger 34 which is urged into its forward, or firing-position, by any suitable means such, for instance, as a helical firing-spring 35.

As is shown particularly well in Figs. 8 to 10` inclusive, the breech-bolt 26 is formed in its under face adjacent and intersecting its forward end, with a relatively-shallow but wide groove 35 having opposed inwardly-facing side-wall portions respectively constituting detent-holding surfaces :i1-31, the rear end of each of which is sloped outwardly and rearwardly to provide a detent-closing cam 38. Rearwardly of the detent-holding surfaces 31-31 and the detentclosing cams 38--38, the breech-bolt 26 is provided with a stud-like depending detent-releasing or retiring abutment 39. The features 31, 38 and 39 are provided for the purpose of controlling the flow of cartridges from the magazine of the firearm in a manner as will more fully hereinafter appear.

The stock 29 is formed with a longitudinal magazine-clearance passage 40 intersecting at its forward end an upwardly-opening cavity 4| also formed in the said stock and accommodating the upper portion of a pivotal-trigger 42. Extending through the said magazine passage 40 and the said cavity 4| in the stock 2|), is a tubularmagazine comprising a tubular housing-member 43 and a tubular cartridge-receiving member 44 tting within the said tubular housing-member 43 in a manner common in tubular-magazine firearms.

Within the tubular cartridge-receiving member 44 is a helical magazine-spring 45 which exerts constant forward pressure upon a cartridgefollower 46 which, in turn, is adapted to thrust forwardly upon such cartridges as may be within the said member 44 and within a magazinethroat 49 as well as certain of those cartridges enroute to the cartridge chamber 25 of the. firearm, all in a manner as will more fully hereinafter appear.

The tubular housing-member 43 of the maga- Zine structure is formed at its front end with a stop-lip 41 projecting beyond the forward end of the tubular cartridge-receiving member 44 and adapted to engage the underside of a rearwardly-extending tubular extension 48 of a magazinethlroat generally designated by the reference character 49, and which will be described in more detail hereinafter.

In the particular firearm chosen for illustration, the stop-lip 41 of the tubular housingmember 43 is maintained in engagement with the tubular-extension 48 of the magazine-throat 49 by means of a helical-spring 50 seated in an upwardly-opening pocket 5| formed in the Stock 29 and leading downwardly from the bottom of the cavity 4| therein. The tubular cartridgereceiving member 44 is thus maintained in axial Y alignment with a tubular cartridge-passage 52 formed in the rear portion of the magazinethroat 49 and extending completely through the tubular-extension 43 thereof.

The forward end of the tubular cartridge-passage 52, just above referred to, intersects an upwardly-opening cartridge-pocket 53 formed in the forward portion of the magazine-throat 49. Formed within the cartridge-pocket 53 just referred to, and extending upwardly along each of the side-walls thereof is a forwardlyand upwardly-inclined cartridge-elevating surface 54 complementing and functioning, for the purpose as will hereinafter appear, in conjunction withk a cartridge-elevating surface 55 sloping upwardly and forwardly and intersecting the forward face of the magazine-throat 49.

The magazine-throat 49 as well as the forward portions of the housing-member 43 and the cartridge-receiving member 44 are received in a longitudinal opening 56 in the lower wall of the receiver 2|. The said magazine-throat 49, and the parts carried thereby, is rigidly coupled to the receiver 2| partly in the longitudinal opening 56 therein and partly within the breech-bolt passage 23 therein, b-y means of a coupling-pin 51 extending transversely through the said magazine-throat 49 and the adjacent flanking portions of the receiver 2|.

Projecting laterally into the upwardly-opening cartridge-pocket 53 in the magazine-throat 49 is the yielding stop-finger 58 of a cartridge-retaining member 59 preferably formed of sheetmeta1 having a spring temper and secured to the said magazine-throat 49 by means of a screw 69.

Just forwardly of its tubular-extension 48 the magazine-throat 49 is formed with a depending mounting-lug 5 l, the forward face of which coincides with the rear surfaces of two substantiallyvertical slots 62-62 one of which is formed in each of the respective opposite sides of the magazine-throat 49 and each of which intersects the cartridge passage 52 in the rear end of the said magazine-throat. Movable in each of the slots (i2-52 in the magazine-throat 49 is a cartridgecontrol lever S3 preferably formed of sheet-metal and mounted for pivotal movement transversely of the path of movement of cartridges through the magazine-throat, upon one of two pivot-pins 64, one of which latter projects forwardly from the mounting-lug 6| adjacent each of the lower outer corners thereof.

Each of the aforesaid cartridge-control levers S3 corresponds to the other save that one is of right-handed form and the other of left-handed form and each thereof is provided adjacent its inner edge with an arcuate cartridge-control abutment 65 substantially conforming in radius to the radius of the body portion of the cartridges to be controlled. At its upper end. each of the cartridge-control levers 63 is formed with an upwardly-and-rearwardly-extending actuating-finger 66 which is oppositely-beveled and adapted to be engaged by the features 31, 38 and 39 of the breech-bolt 26 in a manner as will hereinafter appear.

For the purpose of making clear the operation of the tubular-magazine repeating-firearm above described and illustrated in the accompanying drawings, let it be assumed that the firearm has just been discharged and that the parts are in the positions in which they are illustrated in Fig. l, which figure illustrates the conditions eX- isting at the very briefest instant following the discharge of the firearm.

When the parts are in the positions just above referred to, it will be noted that both of the cartridge-control levers 63-63 are held in their retired or spread position by the detent-releasing abutment 39 of the breech-bolt 26, which at this time is engaged with the tapered actuating-fingers 66 of both of the said levers (see Fig. 4 in particular). With the cartridge-control levers 63 in their retired or spread position as just described, their respective arcuate cartridge-control abutments 65 are withdrawn from the path of movement of the head or flange of a cartridge b. The magazine-spring 45 is thus free to thrust the said cartridge b as well as companion cartridges a and c forwardly until the foremost cartridge c is checked by its engagement with the forward-portion of the underface of the now-closed breech-bolt 26.

With the parts in the positions above referred to, the breech-bolt 26 and associated parts will be kicked back, so to speak, by the energy developed by the discharge of the cartridge d with the effect of extracting and ejecting the nowred cartridge d and shifting the parts into the position in which they are shown in Fig. 2.

Very shortly after the initiation of the rearward 'travel of the breech-bolt 26 as above described, the detent-releasing abutment 39 thereof will have shifted out of engagement with the actuating-fingers 66-66 of the complemental cartridge-control levers 63-63. A slight further continued rearward movement of the breechbolt 26 will next engage the detent-closing cams 33-38 thereof with the respective actuatingfingers 66-66 of the levers (i3- 63. The engagement just referred to will effect the positive inward swinging movement or closing of the said cartridge-control levers 63-63 to thus interpose the cartridge-control abutments 65-65 of the respective levers in the path of movement of the head or flange at the rear end of the cartridge b (see Fig.

After the engagement of the detent-olosing cams 38-38 of the breech-bolt 26 with the actuating-lingers 66--66 of the respective cartridgecontrol levers 63-63 as above described, the detent-holding surfaces 3l-3l will respectively be brought into engagement with the said actuating-fingers by the continued rearward travel of the said breech-bolt, and thus positively retain the said cartridge-control levers 63-63 in their closed or cartridge-stopping positions until such l time as the said breech-bolt returns and again approaches the limit of its forward travel.

By the time that the breech-bolt 26 has fully retired into the position in which it is shown 1n Fig. 2, the magazine-spring 45 acting through the follower 46 and the cartridges a and b will effect the slight forward and upward movement of the cartridge c until the latter cartridge is yieldingly checked by the stop-finger 58 of the cartridge-retaining member 59. The cartridge c as thus shifted and yieldingly halted will be in a position to have its rear face engaged by the forward face of the breech-bolt 26 when the same moves forwardly, as will be presently described.

When the breech-bolt has reached the limit of its rearward travel, as illustrated in Fig. 2, and the energy developed by the just-fired cartridge d has expended its force, the breech-bolt returnspring 21 will assert itself and move the said breech-bolt `forwardly.

The forward travel of the breech-bolt 26 will first bring its forward face into engagement with the rear face of the now partly-elevated cartridge c and the continued forward movement of the said breech-bolt will force the said cartridge c upwardly and `forwardly under the guidance of the cartridge-elevating surfaces 54 and 55 of the magazine-throat 49. The movement of the cartridge c just referred to, under the urge of the now forwardly-moving breech-bolt 26, will overcome the restraining action of the cartridge-retaining member 59 so that ultimately the said cartridge c will be inserted into the cartridgechamber 25 of the barrel 22, as is illustrated in Fig. 3. Also, as the cartridge c is moved Aforward and elevated by the return-movement of the breech-bolt 26 as just described, the two cartridges a and b will travel forwardly under the urge of the magazine-spring 45 until the forward face of the head or flange of the cartridge b comes into engagement with the arcuate cartridge-control abutments -65 of the respective cartridge-control levers 653-63, as is illustrated in Figs. 3 and 6. This action will halt the further forward travel of the cartridges a and b until such time as the forward end of the breechbolt 26 is so far advanced over them as to not permit the cartridge b to tilt or rise up in front of the breech-bolt and thus possibly cause a jam.l

When, however, the breech-bolt 26 does almost reach its breech-closing position, the detent-releasing abutment 39 of the breech-bolt will reengage with the actuating-fingers 66-66 of the respective cartridge-control levers 63-63 and spread or retire the latter so that their arcuate cartridge-control abutments 65-65 are withdrawn from the path of movement of the head or flange of the cartridge b. As soon as the cartridge b is released in the manner just referred to, the magazine-spring 45, acting through the follower 46 and the cartridge a, will move the said cartridge b forwardly into the position formerly occupied by the cartridge c in Fig. 1. Under these circumstances, the cartridge a will have assumed the position formerly occupied by the cartridge b in Fig. l.

The parts of the firearm are now in position for discharging the cartridge c, upon which occurrence the cycle above referred to-will be reeated, with the cartridge b now retained against forward and upward movement by the under face of the forward portion of the breech-bolt 26 and with the cartridge-control levers 63-63 in their retired or non-interfering positions.

From the foregoing, it will be seen that the cartridge-detent mechanism shown and described is not dependent upon individual springs for its proper functioning, but the respective cartridgecontrol levers 63-63 or their equivalent are positively swung toward and away from each other into and out of their cartridge-detaining position and into and out of their cartridge-releasing position.

Furthermore, it will be noted that when the said cartridge-control levers (i3-63 are moved into their closed or cartridge-detaining position, as indicated in Figs. 2 and 5 in particular, the said levers are positively held in such position by the detent-holding surfaces 31--31 of the breechbolt 26 until such time as the said breech-bolt has moved into a position where the release of the column of cartridges can no longer interfere with its proper functioning nor cause a jam.

While the description of operation above given has been in connection with the automatic functioning of the firearm shown, it may here be noted that the breech-bolt 26 and the parts carried and controlled thereby may be manually shifted by force applied to the finger-piece 33 of the action-slide 3|.

Thus, by means of the improvements of the present invention, cartridge-detent means is provided which is simple, reliable and effective in character and which may be manufactured at a relatively low cost.

The invention may be carried out in other specific ways than those herein set forth without departing from the spirit and essential characteristics of the invention, and the present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.

I claim:

1. A repeating rearm-construction including in combination: a receiver; a breech-bolt movable in the said receiver; a magazine positioned to extend below the said receiver and constructed and arranged to successively cause cartridges to be moved upwardly and forwardly into position adjacent the cartridge chamber of the firearm to be engaged by the said breech-bolt for insertion into the cartridge-chamber of the firearm; cartridge-detent means associated with the said magazine and including a cartridge-control member pivoted to the firearm structure about an axis substantially parallel with the path of movement of cartridges from the said magazine; and detent-operating means shifted by the said breech-bolt and including a detent-retiring portion and a detent-closing portion, each successively engaging with and acting upon the cartridge-control member of the said cartride-detent means to shift the same into a cartridgereleasing position and into a cartridge-detaining position.

2. A repeating firearm-construction including in combination: a receiver; a breech-bolt movable in the said receiver; a magazine positioned to extend below the said receiver and constructed and arranged to successively cause cartridges to be moved upwardly and forwardly into position adjacent the cartridge chamber of the firearm to be engaged by the said breech-bolt for insertion into the cartridge-chamber of the firearm; cartridge-detent means associated with the said magazine and including a cartridge-control member pivoted to the firearm structure about an axis substantially parallel with the path of movement of cartridges from the said magazine; and detent-operating means shifted by the said breech-bolt and including a detent-retiring portion, a detent-closing portion and a detent-holding portion each successively engaging with and acting on the cartridge-control member of the said cartridge-detent means to respectively cause the same to successively release a cartridge, check a cartridge and hold a cartridge from the said magazine.

3. A repeating firearm-construction including in combination: a receiver; a breech-bolt mova-l ble in the said receiver; a magazine positioned to extend below the said receiver and constructed and arranged to successively cause cartridges to be moved upwardly and forwardly into position adjacent the cartridge chamber of the firearm to be engaged by the said breech-bolt for insertion into the cartridge-chamber of the firearm; a pair of opposed cartridge-control levers respectively located on substantially the opposite sides of the path of movement of cartridges from the said magazine and each pivoted to the firearm structure about an axis substantially parallel with the said path of movement; and detent-operating means shifted by the said breech-bolt and including a detent-retiring portion and a detentclosing portion each engaging with and acting upon both of the said cartridge-control levers to successively concurrently shift the same away from each other and toward each other to alternately effect the release and the detention of cartridges.

fi. A repeating firearm-construction including in combination: a receiver; a breech-bolt movable in the said receiver; a magazine positioned to extend below the said receiver and constructed and arranged to successively cause cartridges to be moved upwardly and forwardly into position adjacent the cartridge chamber of the rearm to be engaged by the said breech-bolt for insertion into the cartridge-chamber of the firearm; a pair of opposed cartridge-control levers respectively located on substantially the opposite sides of the path of movement of cartridges from the said magazine and each pivoted to the firearm structure about an axis substantially parallel with the said path of movement; and detent-operating means shifted by the said breech-bolt and including a detent-retiring portion, a detent-closing portion and a detent-holding portion each successively engaging with and acting upon both of the said cartridge-control levers to successively retire the same away from each other to release a cartridge, to move the said levers toward each other to detain a cartridge and to hold the said levers in the last-mentioned position until the said breech-bolt approaches its breech-closing position.

5. A repeating firearm-construction including in combination: a receiver; a breech-bolt movable in the said receiver; a magazine associated with the said receiver to successively present cartridges for insertion into the cartridge-chamber of the firearm; a magazine-throat secured to the said receiver adjacent the cartridge chamber of the firearm in registration with the delivery end of the said magazine and interposed between the `same and the said cartridge chamber for conducting cartridges into position to be engaged by the said breech-bolt adjacent the said cartridge chamber; a cartridge-control lever pivoted to the said magazine-throat for swinging movement about an axis substantially parallel with the path of movement of cartridges through the said magazine-throat; and detent-operating means shifted by the said breech-bolt and including a detent-retiring portion and a detent-closing portion each successively acting upon the said cartridge-control lever of the said magazine-throat to respectively cause the same to release a cartridge from the said magazine throat and check the movement of the next succeeding cartridge.

6. A repeating rearrn-construction including in combination: a receiver; a breech-bolt movable in the said receiver; a magazine associated with the said receiver to successively present cartridges for insertion into the cartridge-chamber of the rearm; a magazine-throat secured to the said receiver adjacent the cartridge chamber of the rearm in registration with the delivery end of the said magazine and interposed between the same and the said cartridge chamber for conducting cartridges into position to be engaged by the said breech-bolt adjacent the said cartridge chamber; a cartridge-control lever pivoted to the said magazine-throat for swinging movement about an axis substantially parallel with the path of movement of cartridges through the said magazine-throat; and detent-operating means shiftable by the said breech-bolt and including a detent-retiring portion, a detent-closing portion and a detent-holding portion each successively acting on the said cartridge-control lever to respectively cause the same to release a cartridge from the said magazine throat, to check the movement of the next succeeding cartridge and to hold the said cartridge-control lever in the last-mentioned position until the said breechbolt approaches its breech-closing position.

7. A repeating firearm-construction including in combination: a receiver; a breech-bolt movable in the said receiver; a magazine associated with the said receiver to successively present cartridges for insertion into the cartridge-chamber of the rearm; a magazine-throat secured to the said receiver adjacent the cartridge chamber of the firearm in registration with the .delivery end of the said magazine and interposed between the same and the said cartridge chamber for conducting cartridges into position to be engaged by the said breech-bolt adjacent the said cartridge chamber; a pair of opposed cartridge-control levers respectively located on substantially the opposite sides of the path of movement of cartridges through the said magazine-throat and each pivoted to the latter for swinging movement about an axis substantially parallel with the said path of movement; and detent-operating means shifted by the said breech-bolt and including a detent-retiring portion and a detent-closing portion each successively acting on the said opposed cartridge-control levers to successively retire the same away from each other to release a cartridge, and then to move the said levers toward each other to detain the next succeeding cartridge.

8. A repeating rearm-construction including in combination: a receiver; a breech-bolt movable in the said receiver; a magazine associated with the said receiver to successively present cartridges for insertion into the cartridge-chamber of the firearm; a magazme-throat secured to the said receiver adjacent the cartridge chamber of the rearm in registration with the delivery end of the said magazine and interposed between the same and the said cartridge chamber for conducting cartridges into position to be engaged by the said breech-bolt adjacent the said cartridge chamber; a pair of opposed cartridge-control levers respectively located on substantially the opposite sides of the path of movement of cartridges through the said magazine-throat and each pivoted to the latter for swinging movement about an axis substantially parallel with the said path of movement; and detent-operating means movable by the said breech-bolt and including a detent-retiring portion, a detentclosing portion and a detent-holding portion each successively acting upon both of the said cartridge-control levers to successively retire the same awa-y from each other to release a cartridge, to move the said levers toward each other to detain a cartridge and to hold the said levers in the last-mentioned position until the said breech-bolt approaches its breech-closing position.

9. A repeating iirearm-construction including in combination: a receiver; a breech-bolt movable in the said receiver; a magazine associated with the said receiver to successively present cartridges for insertion into the cartridge-chamber of the iirearm; a pair of opposed cartridgecontrol members respectively movable on substantially opposite sides of the path of movement of cartridges from the said magazine; and detent-operating means shifted by the said breechbolt to positively spread and retire the said cartridge-control members away from each other when the breech-bolt is moved into its breechclosing position and to positively move the said cartridge-control members toward each other when the said breech-bolt is moved into its retired position.

10. A repeating rearm-construction including in combination: a receiver; a breech-bolt movable in the said receiver; a magazine associated with the said receiver to successively present cartridges for insertion into the cartridgechamber of the firearm; a magazine-throat secured to the said receiver in registration with the delivery end of the said magazine and interposed between the same and the said receiver for conducting cartridges thereinto, the said magazine-throat being formed on each of its respective opposite sides with an aperture leading into its interior; a pair of opposed cartridge-control members respectively movable on substantially the opposite sides of the path of movement of cartridges through the said magazine-throat and each having a cartridge-checking abutment projectable through the adjacent one of the apertures in the said magazine-throat; and operating-means shiftable by the said breech-bolt and acting to alternately move the said cartridge-control members to simultaneously retire their checking abutment out of the interior of the said magazine-throat and then to project the same thereinto.

FRANK F. BURTON.

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