Cartridge feeding mechanism for firearms

Sept. 19, 1961

R. S. ROBINSON

3,000,265

CARTRIDGE FEEDING MECHANISM FOR FIREARMS

Filed Oct. 29, 1952

Sheets-Sheet 1

<img file="US3000265A_D0001.tif" />

<img file="US3000265A_D0002.tif" />

INVENTOR

<img file="US3000265A_D0003.tif" />

ATTORNEYS

Sept. 19, 1961

R. S. ROBINSON

3,000,265

CARTRIDGE FEEDING MECHANISM FOR FIREARMS

Filed Oct. 29, 1952 3 Sheets-Sheet 2

<img file="US3000265A_D0004.tif" />

<img file="US3000265A_D0005.tif" />

<img file="US3000265A_D0006.tif" />

Sept. 19, 1961

R. S. ROBINSON

3,000,265

CARTRIDGE FEEDING MECHANISM FOR FIREARMS

Filed Oct. 29, 1952

Sheets-Sheet 3

<img file="US3000265A_D0007.tif" />

ATTORNEYS

United States Patent Office Patented Sept. 19, 1961 which the link shell makes with the cartridge on the other hand, the cartridges are loosely held in their respective link shells for which reason it is desirable in some constructions according to the invention for the arc of 5 embrace of the shell about the body of the cartridge case to be somewhat greater than in known constructions as above described.

Longitudinal control of the cartridge within the shell is achieved according to the invention by a detent or 10 detents which protrude into the rim cannelure, or, if not rimless ammunition, on each side of the rim in the known manner described, whereby the cartridge needs to be thrust forward by a relatively light breech bolt or rammer through the very short distance equivalent to 15 forcing the rim past the detent or detents. When this is done the cartridge is no longer gripped by the link shell and the remainder of the ramming operation through the link shell is accomplished with negligible thrust.

For purposes of brevity, the operation of forcing the 20 rim forward the short distance past the detents is hereinafter known as “clearing.”

Furthermore, in the feed and loading mechanisms according to the invention, the clearing operation may alternatively be effected before each successive belt link is 25 centralized with respect to the bore or gun centerline, and may be performed by another member than the breech bolt or rammer.

For instance, in recoil-operated automatic firearms according to the invention the barrel extension may be con30 structed to incorporate a clearing lug which is laterally located so as to align with the open gap of the belt shell next to, and on the loaded belt side of, the centralized belt link; and is longitudinally located so as to effect the short stroke clearing operation during the last part 35 of the run-out of the barrel assembly at which point the great forwardly directed kinetic energy of the barrel assembly as it approaches full run-out is available to effect clearing of successive belt links during the run-out cycle. It then follows that after the centralizing of the said 40 belt link by the feed pawl system during the recoil cycle, the subsequent ramming of the cleared cartridge from the said link by the bolt or rammer requires relatively negligible energy.

Furthermore, in gas-operated automatic firearms ac45 cording to the invention, a similarly located clearing lug may be incorporated on one side of the piston or bolt carrier component, or as in the case of inertia-locked firearms on one side of the breech bolt, whereby the clearing operation is effected during the last part of the 50 forward movement of the bolt carrier or bolt when a great amount of forwardly directed kinetic energy is available in those members to perform the clearing operation.

In the accompanying drawings:

FIG. 1 is a rear elevational view of a short length of a cartridge belt embodying my invention;

FIG. 2 is a sectional view through one of the belt links showing a cartridge therein on line 2-—2 of FIG. 1;

FIG. 3 is a plan view of an inertia-locked firearm show60 ing the cartridge belt thereon and the clearing and ramming mechanism;

FIG. 4 is a sectional view on line 4—4 of FIG. 3;

FIG. 5 is a top plan view of the breech portion of a recoil-operated firearm showing a cartridge in cleared posi65 tion ready to be thrust into the receiver;

3,000,265

CARTRIDGE FEEDING MECHANISM FOR FIREARMS

Russell S. Robinson, Short Beach, Conn.

(124 Via Yelia, Lido Isle, Newport Beach, Cahf.) Filed Oct. 29,1952, Ser. No. 317,484

Claims. (Cl. 89—33)

This invention pertains to the feed and loading system in belt-fed automatic and semi-automatic firearms of the type in which each round of ammunition in the ammunition belt is thrust forward out of the belt during its stripping or loading operation. The objects of the invention are to simplify the construction and manufacture of the ammunition belt, to lessen the duty of the loading operation from the belt, and to make possible a great reduction in weight and volume of breech bolt and a shortening of the breech action of the firearm.

In known firearms which use a forward-stripping ammunition belt, firstly the belt is constructed so as to support each round of ammunition over part or all of the length of the cartridge case by a belt link which comprises a stiff shell extending around more than half of the arc of the section of the case. The shell of the link is contoured to engage the taper of the body of the cartridge case and to grip it firmly in order to retain the cartridge, and in certain known constructions, longitudinal retention is provided by detents formed into the shell body or extensions therefrom which engage in or around the driving band, case belt, or rim cannelure.

Secondly in these known firearms, the loaded belt links are successively fed to a central position in the gun in approximate alignment with the barrel axis, and the cartridges are forwardly rammed in succession into the firing chamber from the belt links by action of a breech bolt or rammer which thrusts forward through the open gap in each successive link shell, thereby pushing the cartridge forward against the initial grip of the detents and against the continuous grip of the shell until it passes out of the belt link and into the firing chamber or next loading function. .

Tn order to overcome the grip of each link shell and provide a sufficient thrust to insure dependable operation, it is necessary in such known firearms for the breech bolt or rammer to have relatively heavy mass, and to be further constructed so that the said mass has a considerable distance available to run forward before contact is made with the cartridge so that the necessary kinetic energy is available to achieve the stripping of the link under all operating conditions. Also, it will be appreciated that in order to obtain consistent functioning, the quality and thickness of material and dimensions of the belt must be held within close limits.

In feeding and loading mechanisms according to this invention, the ammunition belt may be of the type in which the links are rigidly or flexibly connected together or of the disintegrating type, each cartridge being supported by a link shell constructed substantially as described above, except that the shell does not grip the cartridge, the interior arc or contact points of the link shell which control the cartridge being of substantially the same diameter throughout its length as the maximum diameter of the cartridge case. Thus, owing to the taper of the cartridge case on the one hand, and the cylindrical or parallel nature of the interior contact points

3,(

FIG. 6 is a sectional view on line 6—6 of FIG. 5;

FIG. 7 is a view similar to FIG. 5 showing a cartridge in next-to-centralized position;

FIG. 8 is a sectional view on line 8—8 of FIG. 7 showing a cartridge positioned in the receiver and a second cartridge in next-to-centralized position;

FIG. 9 is a top plan view of a gas-operated firearm showing a cartridge cleared from the belt in next-tocentralized position;

FIG. 10 is a sectional view on line 10—10 of FIG. 9;

FIG. 11 is a sectional view similar to FIG. 10 but showing a cartridge in cleared and centralized position about to be moved into the receiver; and

FIG. 12 is a transverse sectional view on line 12—12 of FIG. 10.

Referring to FIG. 1, a belt of three links of the nondisintegrating type is shown, the two left links being loaded with rimless cartridges and the right link being empty. Each link comprises a substantially open cylindrically shaped shell 1, the inside diameter of which is approximately equal throughout its length to that of the rim and adjacent body of the cartridge 2, and a jacket 3 which partially encloses and is spot-welded or otherwise fixed to the shell 1 and is provided at each side with a flexible coil connector 4 by means of which the links are flexibly joined together to make up the belt. The interior of each shell 1 is provided with a detent 5 which is pressed into the rear right flank of the link shell so as to protrude into the cannelure in front of the rim, thereby preventing the cartridge 2 from freely sliding longitudinally with respect to the shell 1.

FIG. 2 shows a section on line 2—2 of FIG. 1 with the shell 1 drawn in section, a cartridge 2 drawn in full and aligned coaxially with respect to the shell 1, the detent 5 shown as aligning with the rim cannelure.

FIG. 3 is a plan section taken just under the feed cover of the inertia-locked firearm, and it may be assumed that the cover is provided with a pawl feed mechanism, not shown, of well-known type, which feeds the successive belt links from left to right (FIG. 1) during part of the breech bolt recoil cycle and retains them steady during the breech bolt run-out cycle.

Referring to FIGS. 3 and 4, this example comprises a barrel 6, which is fixed to the gun casing 6^a, a breech bolt 7, shown in its rear sear position, of relatively small mass and provided with a spring-urged loading pawl 8 of wellknown type, a feedway comprising a lateral rear cartridge guide 9, a lateral front bullet guide 10, and a belt guide or buttress 11 for supporting the belt against forward movement.

During the loading operation according to this construction of the invention the breech bolt 7 moves forward from its sear position, the loading pawl 8 contacting the base of the centralized cartridge 2 at longitudinal station X and driving the said cartridge forward, the centralized belt link 1 and 3 at the same time being retained in its original longitudinal position by the buttress 11.

The first forward movement of the cartridge from station X requires sufficient thrust against its base to force clear its rim past the detent 5. After the base of the cartridge has passed station X', at which point the cartridge and loading pawl are in the positions shown in dotted lines in FIG. 4, the remainder of the belt link shell 1 offers negligible resistance to the further forward movement of the cartridge during the loading movement.

In all of the three examples described, the extraction of the cartridge case, and its ejection are functions beyond the scope and ambit of this invention and are performed by one of a number of well-known means, the construction of which is not shown.

In the alternative construction according to the invention as shown in FIGS. 5 to 8 inclusive, the firearm is recoil operated and the belt feed is performed by one of the known types of pawl drive mechanisms in which part of the pitch distance between adjacent cartridges is fed 75 )00,265 during the latter part of the run-out of the barrel, the remainder of the pitch distance being fed during recoil of the barrel in such manner that at full recoil a cartridge is centralized in the feedway. Thus, when the gun is recoiled 5 the ammunition belt 31 is laterally positioned as shown in FIG. 5, whereas when the gun is run out (in battery position) the belt 31 is laterally positioned as shown in FIG. 7.

Referring to FIGS. 5, 6, 7 and 8, the firearm according 10 to this construction comprises a gun casing 20 to which is normally fixed a feed cover 21, which incorporates a feed pawl mechanism of the type above described, a rear cartridge guide 22, a belt guide and clearing buttress 23, a front cartridge guide 24 of which the central portion 25 15 is offset forwardly to an extent at least equal to the clearing displacement, a longitudinal cartridge stop 26, a barrel 27 which is fixed to a barrel extension 28 both of which are slidably mounted in the casing 20 to the extent defined between the barrel location in FIG. 5 and FIG. 7, the 20 barrel extension 28 incorporating a clearing lug 29, a lightweight breech bolt 30 which is fitted with a spring-pressed loading pawl of well-known type 30', the bolt 30 being operated by gun recoil and run-out in well-known manner or by means similar to that of my copending application 25 Serial No. 309,193, filed September 12, 1952. In such mechanism the travel of the bolt is considerably greater than that of the barrel.

Fed into the firearm is a belt of ammunition 31 of the type above described, which includes a centralized car30 tridge 32', a next-to-centralized cartridge 32, and a third cartridge 32' (see FIGS. 5 and 7).

The operation of the above construction is such that with the barrel extension 28 and breech bolt 30 in their respective recoiled positions, as shown in FIGS. 5 and 6, 35 the belt 31 has been fully fed so that cartridge 32' is centralized over the boltway of barrel extension 28, the said cartridge 32' having already been cleared by earlier action. As the bolt 30 and barrel extension 28 run forward, the cleared cartridge 32' is pushed out of the belt 31 by 40 the pawl 30' of the bolt 30 and into the firing chamber with negligible resistance. By the time the run-out of the barrel is nearly complete the belt has been fed from the position shown in FIG. 5 to that shown in FIG. 7, and during the last part of run-out the clearing lug 29 strikes 45 cartridge 32 with a very great reserve of energy and forces it forward a short distance to the position it occupies in FIGS. 6 and 7, thereby clearing it of engagement with the detent 5 in the link shell as earlier described.

During the subsequent recoil, the belt 31 is further fed so that when recoil is complete cartridge 32 will occupy the centralized position as shown in FIGS. 5 and 6. Usually in a gun the cartridge belt is fed from left to right relatively to the position of the user. In some in55 stances, however, the feed is in the opposite direction, and for this reason a second clearing lug 29 is provided on the other side of the barrel extension in symmetrical position with the first. It will be understood that only one of these lugs will be operative depending upon the di60 rection of the feed of the belt.

Referring to the third example shown in FIGS. 9, 10, 11 and 12, this construction shows how the clearing funci tion may be performed by a bolt carrier of the type which controls the breech bolt reciprocation and locks it, and 05 usually provides the firing pin energy.

The firearm comprises a gun casing 50 which incorporates a barrel 51, a gas piston 52, and a feed cover 53 which includes and supports a pawl feed system (not shown) of well-known type which feeds and centralizes 70 successive cartridges in the cartridge belt by one full pitch during recoil of the breech bolt system and holds the belt steady during the run-out cycle, and which includes a rear cartridge guide 54, a belt guide and clearing buttress 55, and a front cartridge guide 56 which has a forwardly displaced portion 57, the displacement of which at least

3,000.265 ⁶to engage the cleared cartridge upon the next run out of the barrel to load it into the barrel. . . . .

2. The combination of an interlinked or disintegrating ammunition belt of the type in which cartridges are thrust forward out of each link during loading, each link having a shell, the interior arc throughout the length of the shell is of substantially the same diameter as the maximum diameter of the cartridge to offer no substantial resistance to the forward movement of the cartridge.and having one or more detents which protrude into the interior body of the shell to engage the cartridge sufficiently to prevent its free longitudinal movement, with a firearm comprising a gun casing having means for receiving said belt, a barrel and piston housing fixed thereto, a breech bolt and a piston-carrier controlling the breech bolt, a recuperator for impelling said carrier forwardly, gas-operated means for returning the carrier, and said piston-carrier incorporating a clearing lug offset laterally from the barrel axis which performs the clearing of each cartridge before the latter is fed to the central or loading position, and means on the breech bolt to engage the cartridge after it has been fed to loading position and load it into the barrel.

3. A combination of ammunition belt and firearm according to claim 1 in which a second clearing lug is provided symmetrically on the opposite side of the barrel extension.

4. A combination of ammunition belt and firearm according to claim 2 in which a second clearing lug is provided symmetrically on the opposite side of the pistoncarrier.

5. The combination of an ammunition belt and firearm according to claim 2 in which the clearing of the cartridge is effected during the last part of the forward movement of the piston carrier.

6. The combination of an interlinked ammunition belt of the type in which cartridges are thrust forward out of each link during loading, and a firearm, each link having a shell of generally cylindrical form, the interior arc of , which is substantially constant throughout the length of the shell and of substantially the same diameter as the maximum diameter of the cartridge whereby the shell offers no substantial resistance to the forward movement of the cartridge, said shell having a cartridge-engaging detent projecting inwardly from its wall to engage the cartridge to restrain its longitudinal movement relatively to the shell, said firearm having a casing provided with means to receive said belt, a barrel carried by the casing, a member mounted for longitudinal slidable movement with respect to the casing and offset laterally from the barrel axis to engage a cartridge and clear it from the detent when said cartridge is in an offset position laterally of the barrel axis, said barrel being provided with an extension, said clearing member comprising a lug mounted on the barrel extension laterally of the axis of the barrel, and means for loading the cartridge into the barrel after the latter is centralized with respect to the barrel axis.

7. The combination of an interlinked ammunition belt of the type in which cartridges are thrust forward out of each link during loading, and a firearm, each link having a shell of generally cylindrically form, the interior arc of which is substantially constant throughout the length of the shell and of substantially the same diameter as the maximum diameter of the cartridge whereby the shell offers no substantial resistance to the forward movement of the cartridge, said shell having a cartridge-engaging detent projecting inwardly from its wall to engage the cartridge to restrain its longitudinal movement relatively to the shell, said firearm having a casing provided with means to receive said belt, a barrel carried by the casing, a member mounted for longitudinal slidable movement with respect to the casing and offset laterally from the barrel axis to engage a cartridge and clear it from the detent when said cartridge is in an offset position laterally of the barrel axis, said firearm being provided with a gas-operated ·

equals the clearing displacement, the said portion being laterally located one belt-link space from the center of the gun. The firearm further comprises a breech bolt 58 which incorporates a spring-pressed loading pawl 58' of well-known construction, a piston bolt earner 59 which is urged forward by a spring 60 and which co-reacts in well-known manner with the bolt 58 whereby when the piston carrier 59 is in forward position the bolt 58 is locked to the casing 51, and when the piston-carrier 59 recoils under gas action the bolt 58 is first unlocked j from the casing 50, then locked to the piston-carrier 59, which member it follows throughout the rest of the cycle, all in accordance with well-known practice which is not a part of this invention. .

At the rear end of the piston-carrier 59 is a clearing lug 61 which extends toward the feed side of the firearm a distance of one belt-link space and protrudes up into the feedway so as to effect clearing of the next-to-fed cartridge. ...

Feeding into the firearm is a belt of ammunition including a centralized cartridge 62, a cartridge 62', which is one feed step from a centralized position, and a succeeding cartridge 62.

The operation of the above third construction is such that with the piston-carrier 59 and bolt 58 in their recoiled position and cartridge 62 in position all as shown in FIG. 11, the piston-carrier 59 together with the bolt 58 is urged forward by spring 60 so that pawl 58' thrusts cartridge 62 into the firing chamber of barrel 51. During the last part of the forward movement of piston-carrier 59 the clearing lug 61 strikes the base of cartridge 62' and carries it forward the short distance required to clear its rim past the detent in the belt as already described, the construction then taking up the positions as shown in FIGS. 9 and 10. Following the firing of cartridge 62 the piston-carrier 59 moves back thereby unlocking and withdrawing the breech bolt 58 with the spent cartridge case of cartridge 62, and during the said withdrawal the cleared cartridge 62' is fed over into the central position so that when recoil of the bolt and carrier system is complete, the construction again takes up the position shown in FIG. 11 with cartridge 62' cleared and centralized.

Also in this form of my invention I may provide for a feed of the bolt from right to left by placing a second clearing lug 61 upon the opposite side of the pistoncarrier 59, arranged symmetrically with respect to the one shown in FIG. 12. This clearing lug would, of course, perform no function when the feed was from left to right, but when the feed was in the reverse direction it would perform the clearing function and the lug shown in the drawing would be inoperative.

While I have shown and described some preferred embodiments of my invention, it will be understood that it is not to be limited to all of the details shown, but is capable of modification and variation within the spirit of the invention and within the scope of the claims.