US2478219A - Short round corrector - Google Patents

Description

Aug. 9, E949. L. F. YOUNG 2,478,2l9

SHORT ROUND CORRECTOR Fi'led Aug 3, 1944 2 sheets-snaai 1 Aug. 9, 1949. l F. YOUNG 2,47829 SHORT ROUND CORRECTOR v Filed Aug. s, 1944 2 sheets-sheet a 20 4 |\\1 s' l dl/ f1- 3a i; L\'\" R fa 9 i ff 32 m grvuQ/MM Laut T Yllg Patented Aug. 9, 1949 UNITED smits enfoui peice (Granted under the act of March 3, 1883, as

amended April 30, 1928; 370 0. G. 757) The invention described herein may be manufactui'ed and used by or for the Government for governmental purposes Without the payment to me of `any royalty thereon.

The invention relates to machine gun ammunition feeding mechanism, and While applicable to various mechanism, vhas been here constructed and applied to the feed of present day link belt ammunition into the current Browning machine gun, and particularly the cal. 50 gun used largely l loading, firing and ejector mechanism, Aimpose "l requirements for vfree interaction of the ammunition and gun parts which it has been found diliticult to satisfy, even in the long-developed and extensively used gun named.

Displacement of the bullet too far into the case, which may occur in loading the belt or may occur afterward 'by collision of the belt -with objects, and may readily occur when the neck of the case is not Vtight enough on the bullet, is

the cause of the -actual short round, although fother faults, including uneven loading of ani-'- munition in the belt,- and distorted links are listed under this head.

Where the rou-nd itself is actually short, `when the belt enters the gun the noses of the normal rounds Aare guided and held rearwardly by the bunter plate -or `guide lug at the forward side of the entrance to the feedway, and tlie rounds are positioned properly for engagement of the ex'- tractor in the oase groove. 'The short round, however, will not be so guided by the bunter plate; and is likely te V-be set vtoo lfar forward in the f-eed- Way for the entr-actor `to engage it properly, and this is one of the principal causes of lstoppage under the head of short round. In such case, the cartridge is not drawn from the belt, -no round is loaded, and the' operation of the -gfun ceases after firing of the preceding round. A so-called short round 'may also cause jamming of the link in the link stripper. Vr-'her'e are some twenty more or 'lessV common malfunctions of 4this `gun listed under the head of short `rounds,- but the firs'tytvvo mentioned are Ythe `most serious and frequent. stoppage of such -a gun in an encounter is fraught with liability of the most serious consce quen'ces, among the least of which is failure to overcome a-n enemy in an encounter, giving him the advantage in offense. Usually stoppage from short round during an encounter cannot be remedied in time to enable the gunner to vresume attack or defense, and in most cases where the gun Vis mounted non-flexibly in an airplane, it can only be corrected after grounding of the piane. The import of this in statistics of casuale ties and losses of matriel has spurred numerous efforts to eliminate malfunction due te short rounds, Awithout a satisfactory remedy heretofore. Altho sortie of the prior improvements have been of lpartial benefit, none has warranted adoption as standard manufacture.

The present invention has the avoidance of malfunction due to short rounds as its paramount object, although others of importance are also in view. and have 'been attained, `as will be seen.

Among these is simplicity and low cost-of struc. ture, and production and assembly practice. Also, it is sought to avoid need for modification of conventional ammunition and belt forms, or gun structure already in production and in use in L' very large quantity, and to enable application of the invention to guns already in use at small cost and Without return of the gun to arsenals for modification. The latter steps are being successfully carried out extensively, and comparative preliminary tests as Well as experience in service use show that the short round di-fculty has been eliminated to a great extent by the use of invention.

Another airn in -vievv is to enable the application of the invention to guns already in use, b y -m'en of moderate skill, as mechanics or armorers, and

ical functioning, and ballistic Avalues of the Weapons.

An essential yrequirement for satisfactory per# forman'ce of the invention is to present means which will function as lrequired for either righ-t or 'left feed, Ywithout change, and without Vreduiring rearrangement or removal for the change of direction of `feed.

It is also made unnecessary to remove any parts to aiford access to the receiver or loa-ding mechanism parts,- or for the manipulation of the cover plate. It is an important purpose Ato effect positive guidance of the round in the vfeedw-ay yet leave it comparatively free when at loading position, so that it may have sufc-ien-t 'loose movement'to yield downwardly as the extractor rides over the base ofthe cartridge case, and for free movement in extraction, as Well as avoiding 3 cooking of the round with its butt too high for free passage of the eXtractor thereover.

One of the most Valuable features of the invention is its freedom from liability of impairment by rapid wear, or injury by jamming of belts or rounds due to various causes unrelated to my invention. f

I am aware of practices such as shown in the patent to Green, 2,073,632; Turnbull, 2,098,264, and others, all of which are open to serious if not insuperable objections which are obviated by my invention.

It is an important aim of my invention to avoid working upon the projectile in order to effect the necessary corrections, and tov present anarticle which may be readily adapted to a Wide rangeL of Y variation from standard.

Devices functioning by the use of inclined cam faces to engage the tip of the projectile so as to push the cartridge rearwardly are unsatisfactory for several reasons, among which is the fact that the nose ofthe bullet may be deformed by such a device if the cartridge approaches While much out of line, rendering the course of the projectile erratic on firing. More important is the fact that a frequent cause of short rounds will vnot be remedied, this being the case where Athe projectile is set too far back into the cartridge, in which case the base of the round Willnot extend far enough to the rear to be properly engaged by the extractor even if the nose is accurately guided. Another objection to nose guidance is the tendency to produce a dum dum effect by removal of the Vbullet point and broadening and flattening of the truncated pointI on impact. l

These and other reasons Vhave impelled prlor inventors and myself in the devising of means which would operate without engaging the bullet for the purpose of remedying short lrounds, but to operate on the cartridge or the links of the belt. As a result the later patent to Green, No. 2,121,794, the Turnbull patent and othersl including' the one to'Moore No. 2,327,922, have been issued. The Turnbull device if effective (which experience indicates is unlikely) would remedy only one diculty which falls under the head of short round, viz: that where the extractor strikes ythe, butt of theV cartridge and drives the case forward, as explained in that patent. It presupposes that the round will be a-ccurately vpositioned with the end of the cartridge abutting the rear face of the Turnbull anvilblock I3, 'which would be rare in short rounds.

The second Green patent mentioned seeks to effect both the functions of engaging and camming the front edge of the cartridge case rearwardly and also similarly engaging thefront edge of the link. This device requires a very complicated structural form inthe cam block; it requires a passageway for the bullet which does not permit the loose `freedom of movement of thel bullet which has been considered desirable; will be diflicult to install so as to compensate for variation from standard proportions in gun parts which occur incident to large volume production; it cannot Vbe readily clearedrof detritus; it must be made in alternativeY forms for right and left feed; it is excessively liable to -fracture of the delicate thin cam edge and lip at the upper rear side; it limits the clearway between the cover and receiver so :thatin case of a jammed belt, clearance Vis made difficult; Vit is exceedingly liable to malfunction by variation from standard diametersgof-cartridge neck and metal belt linksfand 4 develops l'xc'essive retardance of the gun action. All of the foregoing objections have been overcome in my invention, which operates by a camming only on the belt links.

The Moore patent is open to most if not all of the objections pointed out in the Green device,

as wellas others. v

Short round difficulties may be due to'slight deformations of links which may occur in the handling of belted ammunition, especially When in long length; and may be due to imperfection of form, especially when a succession of links have similar variances from standard, even if individually within 'the set tolerances, a cumulative displacement being possible in some cases. The distance between the forward edge of the link and the base of the cartridge will usually not vary materially from standard (3.432 inches) in such cases, andr my invention will properly aline the round in most distorted links correctly in re-` lation to the extractor within the tolerance for excess permitted in this dimension, as well as variances in width of the links. v Y

The precession of the firing pin action Vin relation to the bolt movement may in some cases prevent the engagement of the extractor when the round is only very :slightly short, and my invention will permit a wide range of advance of firing time and still avoid stoppage from early timing. y Y v Additional objects, advantages and features of invention reside in the construction, arrangement and combination of parts involved in the embodiment of the invention, as will appear or be understood from the following descriptionl and accompanying drawings wherein:

Figure 1 is a cross section of a gun in which my invention has been incorporated, the cover being raised;

. Figure 2 is a fragmentary enlarg-ed vertical longitudinal section across the cam block and heel .of the cover plate;

Figure 3 is a similar View showing the gun barrel;

Figure 4 is Va horizontal vsection through'the feedwayrwith the cam in place and cover removed, showing the functioning of my inveniton with short Yrounds in course of feeding to the position for extraction from the belt;

Figure 5 isV a fragmentary view similar to Fig. 1 showing the cover closed;

j Figurernis an enlarged top view of the cam block;

VFigure 7 is an enlarged rear `edge elevation of the block;

Figures 8 ,toA lOare plan views of respective modifications of the shape of the cam'faces of the cam block, and in which a continuous longi- -tudinal key rib is provided;

Figure 11 Yis a bottom view of a further modification; Y Y

Figure 12 is a rear edge view thereof. vReferrin-gto the drawings, there is illustrated a portion of the receiver 20 at the feedway 2| of a gun of the kind before mentioned, with the cover .22 in place. ThereA being no changes Whatsoever in the constructionv orfunction of the gun action, the mechanism thereof will not be described or shown except as'it appears with the essential part of my invention.

It has been customary heretofore to provide a channel orfgroove 23 transversely across the underside -of the thick -base or heel portion 24 of the cover, in which Va simple bar rectangular in cross section (the fbraket)f ha-s .heretofore been set,

andere heid by two rivets or screws. This bracket is omitted in my invention, but the groove retained and a hardened steel cam block is provided, having two alined longitudinally extending spaced ribs 2S set snugly in the groove 23 and held by two Allen head screws 2l in the same locations as the screws which formerly held the bracket engaged slidably through the counterbored heel 24 and in tapped holes in :the cam block.

This block 25 as actually used is an elongated blank of hardened steel having a thickness in its body part of somewhat less than one quarter inch, a length equal to the width of the cover heel portion 2d and a maximum width from front to back at its middle of approximately ve eigh-ths inchi Its forward edge 29 is rectilinear vand parallel to the ribs 2K6, the latter being spaced from the edge 2S about one eighth inch, and having a width of nearly one quarter inch, and a height from the body of the block not exceeding the depth of the groove so that it may llt in the groove 23 as heretofore formed on the cover in place of the prior bracket.

At the rear face or cam side of the block a central maximum high vertical flat 3| is presented, extending a distance longitudinally of the 'clock somewhat less than half an inch, and from this face .right and left vertical planiform linkengaging cam faces or edges 32 and 33 extend to the ends of the block, each with a forward inclination at an angle of approximately ten degrees to the plane of the face 3l, the total extent of these cam parts longitudinally of the gun being approximately one quarter inch in the device installed, as heretofore embodied.

Mounted as indicated, when the cover is closed, the face 3l defines the forward limit, or side of the 4path of the cartridge belt links moving through the feedway, and the lower face 3d of the cam block then lies nearly at the level of the upper sides of the necks lof cartridges of the rounds lcarried by the links so that .the angular cam edge 35 formed at the junctions of the cam faces 32 or 33 with the bottom face 34 of the block 25 may engage the extreme forward edges of the passing links and force any rounds which are short toward the rear.

The face 34 may be parallel to the top vface 30 and subjacent face of the heel of the cover, which is also parallel to the horizontal planiform slightly raised forward or bed face 36 of the bottorn of the feedway formed on the receiver. This face 3B constitutes the lower guide surface in the eedway for the necks of the cartridges while moving in the gun to the cartridge stop 3l and link stripper 3B which are located as usual. The forward under face may be relieved, as shown., and slopes upward and forwardly from the face 34.

The top of the receiver in the rear part of the 'eedway is also formed with the usual lower channel way 33 immediately to the rear of the face 36, extending from left to right, in'which the loops of 'the belt links 40 rest while lthe rounds are moving through the feedway. This movement of the rounds is eiected by the same feed pawl El heretofore used in these guns, which .is actuated by 'the same means heretofore familiar in the guns indicated, a holding pawl 42 being located at the lower side of the belt on the gun as before.

In the belted ammunition for these guns, due t0 the link blanks being stamped rapidly from sheet steel stock and being rapidly processed .in

6 the forming machinery, they will be found to vary considerably in diameter, and this is accentuated by variations from standard thickness of the sheet stock from which link blanks are out. Also due to peculiar bending forces developed in .shaping, or spotty imperfections of quality or thickness of the sheet stock, in the forming process the bends in the loops of the links which receive the rounds therethrough will not be uniformly .circular, so that parts .are bulged from a symmetrical cylindrical contour while other parts are nearer the case. However, present link stock a-ffords sufficient edge face 'for my invention to operate thereon without liability of missing, overridlng, or pressure on the `underlying case portion. This is due to the manner in which my device may be accommodated to the errors in spaces, thicknesses and relative locations of parts, at the feedtvay :and in the belt. As at present manufactured, the forward part of the neck loop 50 of the link is not tightly tted to the neck 44 of the cartridge case, but has a minimum inside diameter of .56d inch, and assuming `a minimum tolerated link thickness of 0.039 inch, and a vminimum diameter of the neck of .544, this would .give the minimum height 4of the top of the neck link above the face 3S symmetrically (neck radius .272+link inside radius .280-l-.039=.591). The neck may be assumed to have a maximum outside diameter of .560y inch. With a maximum clearance of .565 inch between the cam face 36 and lower feedway face 36, there would thus .be a minimum working shoulder face at the front of the link above the lower face of the cam of .026 inch, which tests have shown alfords more than ample engagement with my cam to eiect the proper ordering of the rounds in relation to the loading extractor. As minimum dimensions are exceptional and only occasional and do not exist ain a large succession of rounds, there would most Vof the time be available a more extensive edge or shoulder face of the neck link engaged. In the measurements stated above and hereinafter typical extremes of tolerance have been l assumed which may or may not be the same as those of actual practice, but will exemplify the possibilities of application of the invention to present guns, and its workability, with current production. Greater tolerances will fall within the margins of safety still remaining as herein disclosed, while other variances from the tolerances .stated herein giving greater thickness or greater .diameter of the link will be more favorable to my invention.

The manner of limiting the neck nt of the loop 50 permits `its rear conical part 52 to more readily nt to the `shoulder 53 of the case, so that in 'the loading or ammunition rounds in the belt links the neck loop is not liable to initial expansion as the cartridge 'neck enters, and the cartridge is very positively 'stopped in this loop when the case shoulder engages the flared rear lpart of the link. This makes the space relation between the forward edge of the loop and base of the cartridge case subject to very remote likelihood of objectionable deficiency, and contributes to 'the dependability of functioning of my invention.

As may be seen in Figs. 1 and 4, the rounds feeding into the gun pass between laterally proacting narod forward and rearward guide lugs or hunters d3 on the side plates of the receiver, and the spacing between these lues -is somewhat more than the maximum permissible length of the round, which is 5.45 inches in this particular installation.

When a round moves into the feeclway, the neck 44 of the cartridge case 45 will be close to or resting on the forward bed face 36 of the bottom of the feedway, with the bullet 4B clear of the face 36. Assuming that the maximum outside diameter of the neck `permitted is .560 inch, the under face 34 ofthe cam block 25 must clear the feedway bottom at the bed face 36 by at least that distance, but in order to afford some loose movement of the round, and a margin of safety, this clearance is preferably at least .005.inch greater thanthe maximiun possible diameter of the case neck, Yor. .565 inch, in the assumed case. v

:TheJimits of tolerancefor the positioning of the links on the cartridges are based on the distance between the butt face of the cartridge to the forward edge of the neck loopf50 of the link. The minimum is'set at v3.432 inch and the maximum 3.457 inch. Wit-h the round inideal position for engagement of its extractor groove 41 Iby the bill 48 of the extractor 49 of the loading mechanism, the cam face 3| of my cam block should be at a distance of approximately 3.43 inches forwardly from the base face of the cartridge. This takes advantage of the fact that if the base of the cartridge is as muchas one eighth inch-or even more-rearward of the ideal position, the extractor will still function correctly, and so the allowance of excess length between the cartridge base and camming edge of the links 5 imum permissible diameter, say .544V inchl pass, i"

resting on the bed face 36 and taking into consideration the safety factor o'f .005 inch over the maximum` diameter, there Ywould be a possible maximum clearance between the cam and cartridge neck of .021 inch. Remembering the minimum height involved in the neck link of .591 inch it will be seen that there will be a working shoulder face availableat the forward edge of the link of at least .034 inch.

The material of the links is required to be of a hardness ofl 49, Rockwell C, and it may thus be readily Vappreciated that the device obtains an ample Working face on the link upon-which the camming function may be carried out. This also affords a satisfactory margin of safety for variation due to wear and some errors since severe tests have shown that a shoulder face of .018 or less engaged is adequate. Y

In the application of my invention to use, on account of the possible variation from standard in the distance between the under face 5I'of the heel portion of the cover and the bed face 36 of the feedway, it is desirable to complete the manufacture of the receiver and cover before my cam is applied. Variances may occur due to displacevment of the bor-e through the pivot knuckle 54 at the forward end of the cover and in the location of the apertures for the cover pin in the trunnion layered assembly secured together and secured to the top face 3U removably, each layer being onethousandth of an inch in thickness. Initially it should be of the maximum thickness which would be required to meet the maximum space tolerance between the heel 24v and the bed face 36 of the feedways, and aftera gauge measurement is taken showing the actual space existing when the cover is closed, the number of thousandths of an inch in excess of a minimum desired will indicate the number of layers of the shim which are to be retained, the remainder being removed. Y i

'In the preferred embodiment of my invention the under face of the block 25 is formed with a recess v60 vextending from the central rear face of the block forwardly` to the front/edge. In. the block-of Figures 1 to 6 this recess opens through the central fiat 3|, and is arcuate, concentric with the axis of around in loading position against the4 cartridge stop, and has a radius approximately the same'as thatV of the cartridge neck. The depth of the recess is thus approximately .062 measured from the underface 34 of the block adjacent the angular edge 35. Y

It will thusY be seen that by coordinating my cam with the bed face of the feedway in the gun named and taking advantage of the accommodation to longitudinal Variance in one direction of which the-gun mechanism is capable, it has been made unnecessary to incorporate many features and elements of construction heretofore used for remedying most of the malfunctions due to short round, and my single simple form of block accomplishes the desired correction and compensations for variations in gun proportions and dimensions, functioning automatically for either right or left hand feed without change or adjustment and without narrowing the clearway objectionably. It is readily accessible in all surfaces for cleaning and inspection and may be quickly renewed in a few moments by the average gunner by removal of fastening screws and replacement.

In the use of my invention, the gun receiver being assembled except that the cam is not in place, a measurement of the space -between the face 5| of the heel 24 and the bed face 36 of the feedway is taken. Assuming that the maximum tolerance here has been .771 inch and the minimum .736, the difference of .O35 would represent the range of variation which it is necessary to compensate for in the shim 28. Consequently, my cam block could be produced with a body thickness of Y .171 and on the top face 30 of the block there would be applied the shim 28, shaped vin plan to t the rib and made up of thirty five laminae secured together in a manner familiar in the production of laminated shims, and also secured to the upper face of the cam, but manually detachable singly or in such number as required, by using a knife edge or other tool to lift the corner of the part to be removed, after which the-started portion may be peeled off manually. With this arrangement any amount counted in thousandths of an inch by whichk the clearance between the bed face 36V4 and heel face 5| falls `short of .771 inch will represent the number of laminae which are to be removed. Gages suitably marked to indicate the number of layers to 'be stripped may be used. The cover being then opened, the camblock with the remaining portion of the shim still secured thereto is set in place and secured with the screws 21 as'indicated.

In operation of the gun 'the ammunition is prepared and fed `as usual to the gun from either I side, according to the arrangement of the feed mechanism, without special practice or consideration on account of my invention. As the rounds are drawn in by the feed pawl, normally positioned rounds and links will move without material guidance, but will be held accurately in position longitudinally of the gun by the flat 3| engaging the links, when the round is at the loading position, stopped against the forward cartridge stop 3'! and stripper 3S, which-like the extractor and other operative parts-will function as heretofore.

In the event tha-t a short round appears and tends to move in a path too far forward, the loop 5D will engage the inclined cam edge 32 or 33, as the case may be, for right or left feed, and the link, with the `round. carried thereby, will be pressed to the rear in proper operative relation to the extractor and the stripper. Should the cartridge extend to the rear beyond normal, the extractor will ride farther forward thereon but will engage properly on its rearward return movement. The recess G0 will leave the bullet free to move loosely while at this loading position, and particularly vertically so that the heel of the cartridge case may be at a low position to clear the extractor in forward movement, and to yield downward thereto if necessary.

Jams in the feedway sometimes occur which subject the parts therein to severe stresses and shock and it is an advantage of my invention that its parts are practically immune to injury in such manner. The angular edges 35 marking the junction of the lower face 313 with the faces 32 and 33 are preferably of a maximum hardness, so as to minimize wear and denting in case `-T of jams which may force the link edges thereagainst, and under tests these have shown no failures by fracture. They have been found highly effective for the purpose contemplated, in extensive firing tests, with short round defects in the ammunition used.

The form and relation of the cam faces may be considerably varied, as indicated in Figures 8 to 10, the Fig. 9 indicating a continuously curved rear cam edge 55 the central part of which is only slightly arcuate and the ends more pronouncedly curved forwardly. In Fig. l0, the opposite end portions 5E of the rear cam faceY are extended from the ends of the block diagonally inward and toward the rear with only a slight curvature and are merged in a central curved face portion 51 of much shorter radius.

In Fig. 8 a central flat 58 corresponding to the fiat 3| is provided from which respective forwardly curved faces 59 extend to the ends of the block.

The manner of keying the block to the heel 24 may be varied in accordance with any approved practices and other shim forms, or methods of positioning the lower face of the block in relation to the bottom of the feedway may be adopted if found preferable. If closer tolerances in the variations from an ideal clearance between the faces 36 and 5| of the feedway are found possible, an arbitrary medium thickness may be set for my cam block which will function for all dimensions Without the use of a shim; or blocks of two different thicknesses might be used respectively for feedway clearances above and below a medial clearance, taking advantage of the possibility of accommodation of my invention to considerable variances in the depth of edge face of the links engaged by my cam block to operate effectively.

It is notable that immaterial camming action occurs between the iiat 3U and the links so that lil the reduction of the extent of engagement of the flat with the links by reason of the formation of the recess 60, involves small liability of excessive wear or misfunction, it being only necessary to hold the rounds statically at this location after the actual camming has been performed by the edges 35.

As is apparent from the foregoing the presentation of the invention here made, while in detail as to the best form as yet embodied, is purely exemplary and many departures from the specie construction, arrangement and combination of parts, substitution of materials and equivalents mechanical or otherwise may be made without departing from the spirit of the invention presented in the appended claims.

In Figures 1l and 12 there is illustrated a further modication wherein the cam blo-ck is of the same conformation in plan as that first described, andv similarly adapted to engage the groove in the cover and to be secured. It may have a similarly disposed central :dat 6| and right and left cam faces 82 and 63, corresponding to the parts 3|, 32 and 33, and a central arcuate recess 5d corresponding to the one 65 before described. The major area of the under face of the block, however, is relieved as at 55 from lines closely parallel to the faces 5|, S2 and 63, so that a comparatively narrow bearing face 66 remains, extending from the cam faces forwardly. In practice this facehas a dimension of approximately two millimeters at its narrowest part, and is slightly broadened at the outer ends and adjacent the recess Sli. This reduces friction on the passing bullets and economizes the power available for the automatic functions of the gun. As a further contribution in this direction the device of Figures 11 and 12 is also bevelled at each end on the under side as at 61 from the level of the relieved face 65 at least, and extending inwardly longitudinally of the block a distance of approximately eight millimeters, although this dimension may be varied as practice shows to be desirable. The relieved face g 65 is in the present instance about two millimeters above the face 66, although this measurement may be much less, or more without material eilect, a very -slight clearance being sufficient, but it is of advantage to make the clearance suf- .,1 fcient to permit a certain degree of rocking of rounds on an axis transverse to the rounds near the cam faces, so that as the ammunition rattles vertically when its direction is abruptly changed at the entrance to the feedway a minimum blocking effect is achieved by avoiding abrupt camming of the rounds upward or downward. The block still closely approximates a rectangle in cross-section in its body `portion throughout its length.

In case the depth of relief at 65 is decreased from that sh-own, the bevels 6l may extend into the relieved surface 65 a distance as far a-s required t0 afford the desired function.

Alternatively a single rib 2&3' may be formed on the top of the earn as in Figs. 8 to 12 extending the full length of the block if need for shims is avoided, and a single rib 25 may be used, stopping shortof the ends of the block, as in Figs. 11 and l2, and the shirns slotted to fit therearound.

I claim:

1. A short round corrector for link-belted cased ammunition rounds in machine guns wherein a receiver is included having a transverse feedway PrQVided with a raised forward cartridge-necksupporting bottom element and/also having van extractor to engage a round positioned midway of the feedway; said corrector comprising a block of a length approximately equal to the. width of thereceiver of the gun, constructed for fixed attachment to the upper side of the feedway forwardly of the desired path of the belt with the longitudinal axis of the block extending parallel tothe feedway bottom for substantial distances from its middle toward each end and having a thickness sufficient to space its under side from the raised forward lower surface of the feedway a distance equal to the diameter of a case neck of a passing round plus maximum tolerance in corresponding measurement of round elements, the inclusive clearance being less than the thickness of belt link edges, said block having a rear face on each end portion inclined from without said path adjacent the ends of the block rear- Wardly to the rearward limit for position of the belt, said block stopping at said limit, an arcuate recess formed in the under face Vof the block nearly concentric with the axis of a round normally positioned for engagement by said extractor for loading, whereby to clear a cartridge neck slightly, the rearmost inner parts of said rear faces stopping adjacent the sides of said recess, said block having a flat at its rear side above said recess parallel to said path and adapted to form a stop for a cartridge case edge.

2. In combination with a machine gun having a receiver with an ammunition feed passage through which an ammunition belt may operatively pass from either side Yof the gun, a guide element having a rearwardly presented arcuate margin curved symmetrically from its center to each side of the receiver for engagement lwith the belt fed from either side of the gun to shift the belt and ammunition carried thereby rearwardly with respect to the receiver.

3. The combination witha machine gun having a receiver, there being a transverse feed chan-v nel in said receiver through which a cartridge belt of the metallic link disintegrating type is fed in firing the gun, of a guide element secured within said channelltransversely of thegun, said element having a rearward guide edge generally parallel with the direction of movement of the belt therethrough, said edge comprising a rearward central portion'and forwardly slopingV side portions, all' said portions merging into a continuous guide edge, and means removably securing said element to the receiver within the feed channel in such position that said Vguide edge engages and limits the forward edges of each belt link as it is moved into cartridge-extracting position to thereby limit the forwardmost position of the cartridge therein.

4. The combination with a machine gun provided with a receiver having a feed channel therethrough transversely of the gun and into which a cartridge belt of the metallic link disintegrating type is fed in nring the gun, of a guide plate secured within said channel at the top thereof, said plate having its rearward edge shaped to provide a transversely-extending continuous'guide edge having a central portion terminating in forwardly-inclined end portions, said guide edge being constructed and arranged to engage the forward top edge portion of each successive link as it is moved into cartridge-extracting position in said feed channel, to thereby limit the forwardmost position of its cartridge when in position to be extracted from the belt.

5; The combination recited in claim 4, said receiver including a top cover, means rigidly securing said plate to the under side of said cover, and a shim interposed and clamped between said plate and cover.

6.Y The combination recited in claim 4, said receiver including a top cover having a transverse groove in its under side, said plate having a rib fitting said groove, screw means passing through said cover into` said plate to rigidly attach said plate to said cover, and a shim clamped between said plate and cover. Y

LAU'IT FRANKLIN YOUNG.

REFERENCES CITED The following referenlces are ofrecord in the le of this patent:

UNITED STATES PATENTS Number

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