US2790355A - Cartridge aligning means for a firearm - Google Patents

Description

April 30, 1957 R. s. SANFORD CARTRIDGE ALIGNING MEANS FOR A FIREARM Filed Nov. 16, 1951 United States Patent CARTRIDGE ALIGNING MEANS FOR A FIREARM Roy S. Sanford, Woodbury, Conn., assignor to the United States of America as represented by the Secretary of the Army Application November 16, 1951, Serial No. 256,722

4 Claims. (Cl. 89-33) This invention relates to cartridge feeding mechanism for automatic firearms and more particularly to means for guiding unlinked cartridges into the firing chamber of. the firearm barrel.

In most high speed firearms such as machine guns, automatic cannon, or the like, ammunition is ordinarily fed thereto in the form of a flexible belt comprising a plurality of cartridges individually gripped by interconnected articulated links. In one type of firearm, the cartridge belt is intermittently advanced into a transverse feedway by suitable feeding mechanism actuated by the movement of a reciprocal member such as a bolt. The leading cartridge in the belt is moved up into contact with a rectangular stop surface fixedly secured in the feedway of the gun. In this position of the leading cartridge, the link thereon is engaged and positively held in predetermined relation to the face of the bolt and the bore axis of the barrel by pawl mechanism or the like. Thus, as the bolt moves forwardly during counter-recoil, the leading cartridge is stripped from the link engaged therewith and rammed into the firing chamber of the barrel. As the cartridges are stripped one by one, the links become disconnected from one another and are eventually forced out of one side of the gun feedway by the advance of the cartridge belt from the opposite side thereof.

It has been found that difficulties are frequently encountered in guiding the empty links out of the feedway and .in their eventual disposal, particularly when the firearm is mounted in aircraft. Accordingly, it has been proposed to employ an independently operated feed wherein the cartridges are stripped from their links prior to being fed into the gun. Tests have indicated that such a device appreciably reduces the number of gun parts by virtually eliminating the necessity for using the linkpositioning mechanism of the prior art as well as the pawl mechanism for intermittently advancing the cartridge belt along the feedway of the gun.

However, the feeding and chambering of unlinked cartridges introduces new problems in the operation of the gun. For example, it is well known that cal. .60 ammunition is provided with an appreciable taper. It is there fore apparent that if the leading cartridge is stopped in the feedway of the gun by a surface parallel to the bore axis thereof, as is common in the prior art, the taper of the cartridge effects a corresponding inclination thereof relative to the central longitudinal axes of the bolt and the bore of the barrel. Such inclination of the leading cartridge is obviously transmitted to the following cartridges which are being forced into full sidewall contact with one another as a result of the continuous feeding pressure applied by an independently operated feed mechanism. Moreover, the inclination of each cartridge is further increased by its own taper so that when grouped on the feedway of a gun, the noses and bases thereof will lie substantially in arcs of circles. Thus, as the counterrecoiling bolt rams the leading cartridge forwardly, the increase in diameter thereof from the first shoulder to the Patented Apr. 30, 1957 base will cause displacement of the cartridge adjacent thereto against the feeding pressure of the remaining cartridges in the feedway of gun. Consequently, the resultant frictional drag created between the forwardly moving leading cartridge and the one adjacent thereto may be of such extent as to appreciably retard the counter-recoil of the bolt and thereby detract from the optimum rate of fire of the gun.

It is therefore an object of this invention to provide a simple combined cartridge-stop and positioning lever con structed and arranged to guide the leading tapered cartridge of an unlinked group into the chamber of a firearm barrel without imparting any sideways displacement to the cartridge adjacent thereto.

During the employment of the present invention it has been found that in some instances the feeding pressure of the unlinked cartridges entering the feedway of the gun is of such extent that as the leading cartridge moves forwardly past the center of gravity of the cartridge adjacent thereto, the latter will pivot about the base of the former at the point of contact therebetween. Such pivotal movement of the adjacent cartridge adversely affects the guiding action thereof on the leading cartridge and may even result in the incorrect alignment of the latter with the firing chamber of the barrel thereby leading to erratic feeding and the possibility of creating dangerous jamming of the gun.

It is therefore yet another object of this invention to provide in those automatic firearms wherein a plurality of unlinked cartridges are adapted to be successively fed across a transverse feedway, an improved pivotal cartridge-stop and guide lever for the leading cartridge which will also positively block the cartridge adjacent thereto from pivoting about the base of the leading cartridge as the former moves forwardly beyond the center of gravity of the latter.

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

Fig. 1 is a schematic top view of the lever of the present invention showing the position thereof relative to the leading unlinked cartridge of a group disposed on the feedway of a gun immediately after contact between such cartridge and a counter-recoiling bolt.

Fig. 2 is a view similar to Fig. 1 but showing the relative positions of the lever and the leading cartridge a short interval of time after the bolt has moved forwardly toward battery;

Fig. 3 is a view similar to Figs. 1 and 2 but showing the relative positions of the lever and the leading cartridge immediately prior to disengagement from the cartridge adjacent thereto; and

Fig. 4 is a schematic top view of a pair of the guide levers of the present invention arranged to accommodate a cartridge fed downwardly therebetween.

There is schematically illustrated in Fig. l a portion of a conventional automatic firearm to which the present invention is applicable. Such firearm includes a transverse feedway 12 adapted to slidably receive a plurality of continuously fed cartridges which have been delinked by suitable mechanism (not shown) prior to their entry into the gun proper. Each of the cartridges is arranged to be rammed into the firing chamber 14 of a barrel 15 by a counter-recoiling bolt 16 in a manner well-known in the art.

According to the present invention, the transverse movement of the leading cartridge 17 is halted by a lever 18 pivotally secured as shown at 19 to a fixed member 20 projecting upwardly from feedway 12. Lever 18 comprises an arcuately formed body portion 21 extending a tests rearwardly of fulcrum point 19 and an integral nose portion 22 extending forwardly thereof. A hole--23' in lever body portion 21 provides means for holding one end of a spring 24 while the other endthereof is suitably attached -to a fixed. portion (not shown) of feedway-12. The rear end of lever body portion 21 terminates in a laterally projecting lug 25 normally arranged to contact an abutment 26 fixedly mounted onfeedway 12 as lever 18 is pivoted by the bias of spring 24. Thus, lever 18 is fixedly mounted for arresting the transverse feeding movement of leading cartridge 17 while being also mounted for pivotal movement against the bias of spring 24 for reasons which will be hereinafter more fully explained.

Since the cartridges are fed into feedway 12 after being stripped from the links engaged therewith, the continuous pressure of the feed means (not shown) serves to force leading cartridge 17 into simultaneous contact with nose portion 22 and the side of lug 25 of lever 18. At the same time, the remainder of the cartridges lying on feedway 12 are forced into contiguous sidewall relationship with one another. As is well known in the art, the sidewalls of ammunition such as the cal. .60 type are tapered so that the maximum diameter across the base, as indicated by the line A-A in Fig. 3, is appreciably greater than the minimum diameter across the junction of the body portion and the first shoulder as indicated by the line B-B. Accordingly, lever nose portion 22 in the cartridge-arresting position of lever '18 projects laterally relative to the rear end of body portion 21 by an amount substantially equivalent to the difference between diameters A-A and B-B.

Accordingly, lever 18 serves to position leading cartridge 17 so that the longitudinal axis thereof is angularly inclined relative to the longitudinal axes of barrel 15 and bolt 16, as shown in Fig. 1. Thus, at the time bolt 16 picks up leading cartridge 17 for chambering, the bullet end thereof is laterally offset from alignment with the bore axis of barrel 15 while the trailing sidewall of cartridge 17 is disposed substantially parallel thereto. Due to the previously mentioned constant feeding pressure on the cartridges, the one adjacent to leading cartridge 17, hereinafter referred to by the numeral 27, is positioned so that the leading sidewall thereof is also parallel to the bore axis of barrel 15. However, due to the taper of cartridge 27, the trailing sidewall thereof is slightly inclined relative to the bore axis of barrel 15. Each of the remaining cartridges is therefore also inclined to a successively greater degree so that the noses and bases thereof lie in a slight but substantially arcuate path.

As bolt 16 moves cartridge 17 forwardly, the leading sidewall of adjacent cartridge 27 serves to guide the firstmentioned cartridge in a path parallel to the bore axis of barrel 15. In this path of movement, the increase in diameter of cartridge 17 at the point of contact with nose portion 22 of lever 18 pivots such lever about fulcrum 19 against the bias of spring 24. The pivotal movement of lever 18 swings lug away from fixed abutment 26 and behind the base of cartridge 17. It should be here noted that the center-line of bolt 16 lies on a lower horizontal plane than feedway 12 so that the rear end of lever 18 will be above the top surface of bolt 16 as it swings behind the base of cartridge 17. Due to the curvature of lever body portion 21, cartridge 17 continues to be contacted thereby at two separate points despite the swinging movement of lever 18. Thus the bullet end of cartridge 17 moves into the chamber 14 of barrel 15 at a slight angle to the bore axis thereof and eventually contacts the interior wall surface of chamber 14 whereupon such cartridge is guided into full seating position in chamber 14 during continued forward movement thereof. Lever 18 permits cartridge 17 to move forwardly without deflecting adjacent cartridge 27 and the rest of the cartridges in feedway 12 as would ordinarily be the case if a fixed cartridge guide were employed.

When the base of leading cartridge 17 moves beyond the center of gravity of adjacent cartridge 27, lever 18 i has been pivoted sufficiently to bring the rear end thereof into contact with the rim of adjacent cartridge 27 as shown in Fig. 3. Thus, cartridge 27 is prevented from pivoting about the point of contact thereof with the rim of leading cartridge 17 and nullifying the desired guiding effect thereon.

In some firearms, unlinked cartridges are fed one by one downwardly in front of a counter-recoiling bolt from a point above the feedway. In order to eliminate any difficulties in guiding vertically fed cartridges into the firing chamber of a barrel, the present invention also contemplates a pair of guide levers 28 operative on the tapered sides of the cartridge during the chambering movement thereof. As illustrated in Fig. 4, levers 28 are pivotally mounted as at 29 to fixed portions 30 of a feedway (not shown). Springs 31 are arranged to keep laterally projecting lugs 32 on levers 28 against fixed abutments 33. These springs 31, however, are attached at a point much closer to the rear end of levers 28 than is the case in lever 18 of Figs. 1-3. Nevertheless, levers 28 operate in substantially the same manner in that they pivot against the bias of springs 31 as a cartridge 34 is moved forwardly by a bolt 35'. The symmetrical increase in taper rearwardly along the body of cartridge 34 serves to simultaneously pivot levers 28 in opposite directions about fulcrum points 29. Due to the shape of levers 28, the rear ends thereof maintain equal contact with the base of cartridge 34 and thereby guide such cartridge in an undeviating straight line. Thus, cartridge 34 is guided along an axis coinciding with the bore axis of a firing chamber (not shown) despite the taper which produces a continuously increasing diameter at the point of contact with the forward ends of levers 23.

I claim:

1. In combination with a firearm having a barrel and a reciprocable bolt for chambering the leading cartridge of an unlinked group of tapered cartridges, the improvement comprising lever means pivotal about a fixed point adjacent the front end thereof, fixed means operative on the rear end of said lever means for stopping pivotal movement thereof in one direction, and spring means normally urging said lever means into contact with said fixed means, said lever means being arranged to initially position the leading cartridge in the path of counter-recoil travel of the bolt, said lever means having a continuously varying periphery coacting with the leading cartridge to compensate for the increase in diameter between the first shoulder and the base of such cartridge during forward movement thereof by the bolt whereby said lever means serves to guide the leading cartridge along a path in axial alignment with the bore axis of the barrel.

2. The combination defined in claim 1 wherein said lever means comprise a pair of oppositely disposed levers. spaced apart to receive the leading cartridge therebetween, said levers being arranged to simultaneously pivot about said fixed point in the feedway in accordance with the increase in diameter of the leading cartridge at the point of contact thereof with the front end of each of said levers as the bolt moves the leading cartridge forwardly whereby the taper thereof does not change the axial alignment with the centerline of the barrel.

3. In a firearm having a transverse feedway arranged to receive a plurality of continuously fed unlinked tapered cartridges in juxtaposition with one another, a barrelhaving a firing chamber therein, and a reciprocable bolt for chambering the leading cartridge, the improvement comprising a convexly formed lever pivotally mounted adjacent the front end thereof at a fixed point on the feedway, a fixed abutment on the feedway operative on the rear end of said lever to prevent pivotal movement thereof in one direction, and spring means normally urging the rear end of said lever into contact with said fixed abutment, the front end of said lever projecting laterally relative to therear eud thereof by an amount equivalent to the difference in diameter taken at the first shoulder and at the rim of the leading cartridge, said fixed pivot point and said fixed abutment being located relative to one another so as to position the front and rear ends of said lever for simultaneously arresting the transverse feeding movement of the leading cartridge whereby the longitudinal axis thereof is inclined relative to the bore axis of the firing chamber, the trailing sidewall of the leading cartridge and the juxtaposed sidewall of the cartridge adjacent thereto being thereby placed in parallelism with the bore axis of the firing chamber whereby the adjacent cartridge and said lever guides the leading cartridge into the firing chamber of the barrel Without displacing the cartridge adjacent thereto.

4. In a firearm having a transverse feedway arranged to receive a plurality of continuously fed unlinked tapered cartridges in juxtaposition with one another, a barrel having a firing chamber therein, and a reciprocable bolt for chambering the leading cartridge, the combination of a lever pivotally mounted adjacent the front end thereof at a fixed point on the 'fcedway, 'a laterally projecting lug on the rear end of said lever, 21 fixed abutment on the feedway operative on said lug to prevent pivotal movement on said lever in one direction, spring means fixed at one end in the feedway and attached at the other end to said lever between said pivot point thereof and said lug thereon whereby said lug end of said lever is normally biased toward said fixed abutment, a convexly curved body portion on said lever extending from said lug to terminate beyond said fixed pivot point in a nose portion projecting laterally relative to said lug end by an amount equal to the difference in diameters taken at the first shoulder and at the rim of the leading cartridge, said nose portion and said rear end lug portion being thereby arranged to simultaneously arrest the transverse teeding movement of the leading cartridge whereby the longitudinal axis thereof is angularly inclined relative to the bore axis of the firing chamber, the trailing sidewall of the leading cartridge and the juxtaposed sidewall of the cartridge adjacent thereto being thereby placed in parallelism with the bore axis of the firing chamber, the curvature of said lever body portion being such that the rear end of said lever contacts the rim of the cartridge adjacent the leading cartridge approximately at the instant the rim of the leading cartridge moves beyond the center of gravity of the adjacent cartridge whereby the latter cartridge is prevented from tilting about the rim of the former during the remaining contact between the juxtaposed sidewalls of the two cartridges, all adapted and arranged whereby the leading cartridge moves forwardly for chambering alignment without displacement of the cartridge adjacent thereto.

References Cited in the file of this patent UNITED STATES PATENTS 2,073,632 Green Mar. 16, 1937 2,372,462 Webb Mar. 27, 1945 2,701,504 Schaieh Feb. 8, 1955

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