US3527137A - Expendable case ammunition - Google Patents

Description

United States Patent [72] Inventor John J. Scanlon Monroe, Connecticut [21] Appl. No. 786,597 [22] Filed Dec. 24, 1968 Continuation-impart of Ser. No. 686, 508, Nov. 29, 1967, now Pat. No. 3,485,170 [45] Patented Sept. 8, 1970 [73] Assignee Remington Arms Company, Inc.

Bridgeport, Connecticut a corporation of Delaware [54] EXPENDABLE CASE AMMUNITION 14 Claims, 7 Drawing Figs.

52 0.8. CI 89/1, 42/1, 89/1.816,89/14,102/38, 102/43 .[51] Int.Cl F411 1/00, F42b 9/06 [50] Field ot'Search 89/ 1, 14,1.3,1.8l6,1.706;42/1;102/38,93,94,43

[56] References Cited UNITED STATES PATENTS 255,878 4/1882 McGee 102/38 2,919,629 l/l960 Abramson 89/1 .706X 2,987,965 6/1961 Musser 89/l.706 3,048,849 8/1962 DeCaro et a1 102/38 3,288,066 11/1966 Stadler et ai.. 102/38 Primary Examiner-Samuel W. Engle Attorneys-John H. Lewis, Jr. and Nicholas Skovran ABSTRACT: A combination gun chamber and plastic expendable cartridge case designed to permit the cartridge case to be expelled from the muzzle of the gun along with the projectile means. A free expansion chamber is provided between the cartridge case and the chamber bore to permit the case to deform upon firing to take up some of the initial shock of firing and allow the projectile means to get started through the gun barrel before the cartridge case buckles and is expelled. The free expansion chamber results in higher velocities at lower pressures. A relieved expansion chamber can also be provided between the rear of the cartridge case and the gun chamber bore. This relieved expansion chamber functions to lessen the frictional drag of the cartridge case on the wall of the chamber bore to facilitate the expulsion of the cartridge case from the gun barrel.

Patented Sept. 8, 1970 3,527,137

Shet 1 of 2 Inventow zz 74 24 John dscanlon CW Hm Attorneys Patented Sept. 8, 1970 f w m NW WM [H I Inventow John J. ScanIon Attorneys EXPENDABLE CASE AMMUNITION This application is a continuation-in-part of my copending application Serial Number 686,508, filed November 29, 1967, entitled Expendable Case Ammunition", now U.S. Patent No. 3,485,170.

i This invention relates to cartridges and firearm modificavolume of a gun chamber with the free expansion feature is greater than a normal chamber such as shown in application Ser. No. 686,508, i.e., a chamber having substantially the same configuration as the cartridge case. Assuming everything else to be the same, it would be expected that a greater gun chamber volume should produce less pressure and also less projectile velocity. However, it was found that although the pressure in the gun chamber with the free expansion feature didin fact decrease, the velocity of the projectile actually increased.

It was found that although the ballistic efficiency was improved with the free expansion chamber, case expulsion was not substantially improved. The investigation was then directed back to the cartridge. Such parameters as bullet pull, annealed and unannealed cases, propellant relative quickness,

. and primer charge weight were re-evaluated. It was found that cases which must be recovered in the field for re-use (particularly the larger artillery cases). Caseless ammunition is also cheaper and can have real functional advantages. In addition,

because the entire cartridge is consumed or expelled from the I gun, the gun system can be simplified over conventional guns which requirejelaborate extraction and ejection means. For purposes of this discussion, combustible cases, wherein the casing is made of a combustible material, are included with caseless ammunition.

The present invention relates to another approach which avoids some of the problems encountered with caseless ammunition and which enjoys almost all of the advantages of caseless ammunition.

Caseless ammunition has not been widely accepted to date because of certain disadvantages which have not as yet been overcome. Thus, caseless cartridges are not waterproof, are structurally weak, and are susceptible to premature or undesirable ignition due to cigarettes, cook-off in a hot gun chamber (especially automatic gun systems), and the like. Solid propellants for such cartridges have a tendency to break up when being handled or loaded, particulary in automatic or autoloading firearms. At present, dimensional control of the propellant is difficult-and costly to attain and must be done by grinding or machining.

The present velocities available in conventional ammunition, i.e., with metal cases, have been limited by the pressure that can be contained safely by existing guns and ammunition cases. In either a caseless or expendable cartridge, the pressure and consequently the velocity is not limited by the strength of a conventional case. It has long been known that firearms can be designed and made which will be able to withstand much higher pressures than presently made and limited by conventional brass cases. The limiting factor then becomes the gas seal which must replace the obturating function now being performed by the metal cases.

Thepresent invention provides an expendable plastic cartridge case which is expelled from the muzzle of the firearm along with the projectile means, whether shot pellets, single bullet, or rifled slug. The plastic body protects the propellant during storage and handling from moisture and unintentional ignition and provides structural rigidity as well. An expendable cartridge made from such a body is only slightly heavier than equivalent caseless ammunition but, on the other hand, it avoids or substantially minimizes the problems mentioned above.

During extensive evaluation of the expendable case disclosedin application Ser. No. 686,508, cited above, it was found that occasionally some of the cases would not be completely expelled from the muzzle. This incohsistency of expulsion was believed to be caused by variances in the quality and quantity of priming material as well as physical properties of the plastic material of which the cartridge case was made. Consequently, it was thought that the number of failures could be reduced if the forward projectile-containing portion of the expendable cases were provided with some free expansion before the, expendable cases were forced through the bore.

When the expendable cases were fired with a free expansion chamber, a new and unexpected result was achieved, i.e., in-

creased ballistic efficiency. This was unexpected because the the case expulsion rate could be changed by making small variations in the primer weight, e.g., case expulsion was better at lower primer weights, presumably because of reduced frictionfcaus'ed by reduced expansion of the cartridge case wall against the gun chamber bore wall in an early stage of the ignition process. Since it is almost impossible to keep the primer material exactly the same in different lots and also to keep the primer weight exactly the same in manufacturing and loading operation, in order to overcome the effect of inconsistent primer weight on the case expulsion rate, the rear portion of the gun chamber was opened up-or relieved for different lengths. Apparently, the opened chamber around the cartridge cases permits the plastic cases to expand radially without either touching the chamber wall or if it does touch, it does so with less gripping force.

It can be seen that it is a major object of this invention to provide a modified gun chamber and expendable cartridge case which will have an improved ballistic efficiency.

Another object of this invention is to provide a free expansion chamber into which the expendable cartridge case can move prior to being expelled from the gun.

Another object of this invention is to provide a relieved chamber which facilitates the expulsion of expendable cases from the gun.

Another object of this invention is to provide an expendable cartridge and gun chamber having an improved ballistic efficiency and case expulsion rate.

Other objects will be apparent from the specification and drawings in which:

FIG. 1 is a sectional side elevation of a loaded expendable cartridge in position in the chamber of a firearm;

FIG. 2 is a side elevation of an expendable body shotshell positioned in a gun chamber;

FIG. 3 is a side elevation view of an expendable cartridge positioned in a gun chamber which has a free expansion chamber at the front thereof;

FIG. 4 is a side elevation view of an expendable cartridge positioned in a gun chamber which has a relieved chamber at the rear thereof;

FIG. 5 is a side elevation view of an expendable cartridge positioned in a gun chamber which has a free expansion chamber and a relieved chamber;

FIG. 6 is a side elevation view of an expendable body shotshell positioned in a gun chamber which has a free expansion chamber; and

FIG. 7 is a side elevation view of an expendable body shotshell positioned in a gun chamber wherein a longer free expansion chamber is provided than is shown in FIG. 6

Expendable cartridge comprises a plastic body member which has a rear tubular portion 22 and a front tapered portion 24. A transverse wall member 26 is integrally formed intermediate to the ends of the body member 20 to define a propellant cavity 28 and a projectile cavity 30, The underside surface 26a of wall member 26 is radiused so as to insure that the force of the propellant cases will be equally distributed across the entire wall member. Although the drawings show a spherical radius, smaller radii will also work, e.g., fillets at the corners. The tapered. body portion 24 has a thin, tubular mouth portion 32 into which a projectile 34 is inserted so that it fits into the projectile cavity 30. Projectile 34 can be held in the projectile cavity by any conventional means including interference fit, adhesives, etc.

, A'propellant means 36, either molded into a unit, loose, or even liquid, is inserted into the open-ended propellant cavity 28. A molded propellant primer cup 38 is attached to the rear end of tubular portion 22 to close off the cavity 28 and prevent the loose propellant powder shown in FIG. 1 from dusting out or extraneous matter from working into the propellant cavity. Primer cup 38 can be secured to the tubular portion of the body member by gluing the cup to the body or by providing a snap-groove means or any other well-known means. Positioned centrally of the primer cup is a suitable solid or molded primer 40 secured by friction or other means such as an adhesive in a pocket formed in the primer cup.

Primer 40 is covered by foiling paper (not shown) and the rear or breech end of the propellant-primer assembly is sealed by a thin film of suitable plastic (not shown) or any other means which will waterproof the propellant-primer assembly while providing the necessary compatibility and structural integrity with the rest of the cartridge case.

The barrel 18 includes an abutment 18a against which the 1 cartridge mouth end 32 abuts to limit the insertion of the cartridge case into the gun chamber. The gun chamber bore 12a then follows the configuration of the expendable cartridge so that the cartridge case is supported by the bore 12a substantially along its entire length.

The expendable cartridge discussed above is the subject matter of co-pending application Ser. No. 686,508, cited above. FIG. 1 of the present application is taken from application Ser. No. 686,508. The present invention improves on the gun chamber shown in FIG. 1 to effect the objectives and ad' vantages mentioned above.

FIG. 2 also shows a combination gun chamber and expendable shotshell cartridge to which the present invention has utility. This specific expendable shotshell body and chamber is the subject matter of co-pending application Ser. No. 755,649, filed August 27, 1968, by Martin W. Kordas, et al. entitled Expendable Shotshell.

FIG. 2 shows an expendable shotshell cartridge 42 which comprises a tubular member 44 and an imperforate transverse wall member 46, which with the tubular member, defines a forward open-ended projectile cavity 48 and a rear openended propellant cavity 50. A projectile means 52, e.g., a rifled slug as shown in FIG. 2, is inserted and secured in the projectile cavity by any well-known means. One or more conventional wads 54 may be positioned between the transverse wall member and the projectile. Positioned in the propellant cavity 50 and secured thereto by any conventional means is a propellant means 56, either molded, loose, or liquid. FIG. 2 shows a molded propellant and includes a pocket into which a primer 58 is inserted and secured. An outwardly projecting flange 60 is integrally formed with said tubular member 44 and extends forwardly for some portion of the length of the cartridge case. Co-pending application Ser. No. 755,649 shows varying flange lengths. It is noted that the front end 44a of the tubular member 44 and the front end 62 of the flange 60 abut against corresponding abutments 64 and 66 respectively in the gun chamber to position and support the cartridge 42 in the chamber.

FIG. 3 shows an expendable cartridge 10 similar to that shown in FIG. 1 positioned in a modified gun chamber which incorporates the present invention. Instead of the loose propellant means 36 shown in FIG. 1, FIG. 3 shows a molded propellant charge 36a with a primer 68 secured directly thereto. It can be seen that instead of following the configuration of the tapered body portion 24 forwardly of point a, the

' forward end 12b of gun chamber bore 12a extends forwardly at an angle to the tapered peripheral surface 24a of tapered body portion 24 so as to define a space 70, which for want of a better term, we will call a free expansion chamber. It should be appreciated that although FIG. 3 shows the forward end 12b of the gun chamber bore as extending forwardly from point a in the same plane as the rear portion of the bore, good results can be obtained by other configurations, as long as excess volume is provided in this location into which the forward projectile-containing portion of the plastic cartridge case can expand so as to lessen the frictional grip that the cartridge case exerts on the projectile.

Point a in reality is a peripheral edge rather than a point and is intended to indicate the forwardmost point or edge on the outside periphery of the body member 20 which is in bearing or supporting relationship with the corresponding portion of the gun chamber bore 12a. As can be seen, the diameter at this point or edge is the maximum diameter of the body member 20. In FIG. 3, the entire peripheral surface of the body member rearwardly of point a would be a bearing means 72 which would be adjacent to and cooperate with bearing support means 74 on the gun chamber bore 12a. However, as will be explained later, the bearing means need not extend all the way to the rear end of the body member.

Upon ignition of the primer and the propellant, the explosive gases act against transverse wall member 26 to move the cartridge case and associated projectile 34 forwardly. The projectile immediately enters the gun barrel 18, whose bore diameter is such that the projectile substantially fills the barrel bore. The plastic cartridge case, since it is prevented from entering the gun barrel with the projectile, moves forwardly into the free expansion chamber 70. Barrel abutment 18a acts as a stop means for the cartridge mouth end 32 before firing and for a period after firing until the projectile leaves the cartridge mouth end and completely enters the barrel whereupon the expendable cartridge deforms inwardly and follows the projectile out of the gun barrel. As far as can be determined to the present, it is believed that the presence of the free expansion chamber permits the plastic cartridge case to expand into the expansion chamber so as to lessen the force with which the cartridge case grips the projectile thus releasing the projectile sooner and with less frictional resistance and thus increasing the projectile velocity while at the same time decreasing the pressure.

The enlarging of the gun chamber to provide the free expansion chamber resulted in higher projectile velocities at lower pressures in the gun. This increase in ballistic efficiency was quite unexpected and provides a new concept in chamber design for expendable cartridges.

FIG. 4 illustrates a second and separate new concept in chamber design for expendable cartridges. It was found that variances in the primer mix sometimes affected the expulsion rate of the expendable cartridges. It was theorized that certain individual primers caused the tubular rear portion 22 of the cartridge case to grip the walls of the gun chamber bore 12a with too much force or perhaps, too soon, and thus caused the forward tapered portion 24 to tear away from the tubular portion 22 which then sometimes became lodged in the chamber bore arid was not expelled from the gun. This excessive or premature gripping of the chamber bore wall was avoided by relieving the chamber bore, as shown by reference numeral 76 in FIG. 4. FIG. 4 shows the relieved chamber 76 with the front end of the chamber bore of similar configuration as the tapered body portion of the cartridge case. It should be noted, however, that the two concepts, i.e., the free expansion chamber 70 and the relieved chamber 76, can be combined, as shown in FIG. 5.

The relieved chamber 76, by reducing the gripping force of the tubular cartridge portion against the chamber bore, is very port means corresponds to the adjacent area on the wall of chamber bore 12a.

FIGS. 6 and 7 are essentially the same except that by reducing the length of the cartridge flange 60a from what is shown in FIG. 2, a free expansion chamber 78 can be formed into which the expendable shotshell body can move upon firing. Obviously, the configuration of the chamber bore 80 can be changed to end up with the same result, i.e., a space or free expansion chamber 78 between the cartridge and the chamber bore into which the cartridge case can move upon firing. FIG. 6 shows a flange 60a which is shorter in length than flange 60 of FIG. 2 while FIG. 7 shows flange 6012 which is approaching the minimum flange possible. Flange 6% functions primarily as an edge to which a gun ejector may catch although it also acts to reinforce the end of the case.

The concepts which form the basis for this invention have been tested and proven from small arms ammunition up to and including large artillery rounds. The materials used for the cartridge cases have included Lexan polycarbonate, polyethylene, glass-filled polycarbonate, and glass-filled polyethylene. Obviously, other plastics having similar physical properties can be used.

retain; l. A firing system in which the projectile means and associated cartridge case are expelled from the muzzle of a firearm, said cartridge case being made of deformable plastic material and comprising an elongated, generally tubular member having a relatively thin mouth end which is adapted to buckle upon firing and a breech end at the opposite end thereof, transverse wall means integrally formed intermediate said ends to form with said elongated member an open-ended propellant cavity at the breech end and an open-ended projectile cavity at the mouth end, projectile means positioned and secured in said projectile cavity, propellant means and ignition means positioned and secured in said propellant cavity, said firearm from which said cartridge case is to be expelled after firing comprising a gun chamber in which said cartridge is positioned for firing, means abutting the mouth end of the cartridge to limit forward movement of the cartridge prior to firing and to give support thereto during firing, the forward end of said gun chamber defining with the forward end of said cartridge case a free expansion chamber into which the cartridge case can expand upon firing thus lessening the overall explosive pressure and increasing the velocity ofthe projectile.

2. In combination with a plastic expendable cartridge having a front mouth end and a rear breech end, transverse wall means integrally formed intermediate said ends to define with said cartridge a projectile cavity and a propellant cavity, projectile means and propellant means secured in said respective cavities, a gun chamber comprising a bore which opens into a receiver means at one end and into an axially aligned barrel at the other end, said bore being adapted to slidably receive said plastic cartridge, means abutting the mouth end of the cartridge to limit the depth of insertion of said cartridge into said bore, the ,configurationof saidboreand the forward end of the cartridge case being such as to define a free expansion chamber into .which the plastic case can expand upon firing, thus providing additional chamber volume for the explosive gases prior to expulsion of the projectile means and the cartridge case from the forward end of the gun barrel.

3. The combination recited in claim 2 in which said plastic expendable cartridge case tapers from an area intermediate the ends thereof, where the cartridge: case is of maximum diameter and where the cartridge case is in substantial bearing relationship with said bore, to the front mouth end thereof, the front end of said bore being angularly displaced relative to said tapered portion of the cartridge case thus defining said free expansion chamber.

4. The combination recited in claim 3 in which a relieved chamber means is provided rearwardly of said area where the cartridge case is in substantial bearing relationship with said bore, said relieved chamber means comprising at least a portion of said bore being expanded to a greater diameter than the portion of the bore corresponding to the area where the cartridge case is in substantial bearing relationship with said bore.

5. A firing system comprising an expendable cartridge case adapted to be expelled from the forward end of a firearm along with the associated projectile means, said cartridge case comprising a plastic body member open-ended at both ends and having a transverse wall member integrally formed therewith to define a projectile cavity and a propellant cavity, projectile means and propellant means secured in said projectile cavity and propellant cavity respectively, a gun chamber comprising a bore which opens into a receiver means at one end and into an axially aligned barrel at the other end, said bore being adapted to slidably receive said expendable cartridge, means limiting the depth of insertion of said expendable cartridge into said bore, and a relieved expansion chamber defined by said bore and the corresponding portion of the expendable cartridge which permits the explosive gases which are set free by igniting the propellant means to act against the transverse wall member and the projectile means to start the projectile means moving through the barrel while at the same time deforming the plastic cartridge case into the expansion chamber thus reducing the force with which the cartridge case grips the chamber wall.

6. A firing system as recited in claim 5 in which said body member has a bearing portion intermediate the ends thereof, bearing support means on said bore corresponding to and having a diameter slightly greater than said cartridge bearing portion, said relieved expansion chamber being located rearwardly of said bearing portion and said bearing support means and comprising at least a portion of said bore having a diameter greater than the diameter of said bearing support means.

7. A firing system as recited in claim 6 in which said body member tapers forwardly from said bearing portion, and said bore extends forwardly from said bearing; support means at an angle to said tapered body member thus defining a free expansion chamber therebetween.

8. A firing system as recited in claim 5 wherein said body member comprises a tubular portion of constant diameter and a tapered portion extending forwardly therefrom, said bore having a stepped chamber comprising a front section, of a diameter slightly greater than the outside diameter of the tubular portion of said body member, extending rearwardly past the front end thereof to provide a bearing support means therefor, said tapered body portion and said front bore section defining a free expansion chamber forwardly of said bearing support means into which the cartridge case can deform and move after firing prior to being expelled from the gun barrel, a second bore section having a diameter greater than said front bore section defining with said body tubular portion said relieved expansion chamber rearwardly of said bearing support means.

9. In combination with a deformable plastic expendable cartridge case in which said cartridge case comprises a body member open-ended at both ends and having a transverse wall means integrally formed intermediate said open ends, said body member having a bearing surface which begins at a point adjacent said transverse wall means and extends rearwardly for at least a portion of the length of said body member, a tapered outer surface of said body member extending forwardly and inwardly from said point to the mouth end of the case to define an angularly shaped member which tapers from the mouth end to the bearing surface adjacent said transverse wall means, a projectile cavity located forwardly of said transverse wall means and a propellant cavity formed rearwardly of said transverse wall means, projectile means and propellant means secured in the respective cavities, a gun chamber comprising a bore which opens into a receiver means at one end and into an axially aligned barrel at the other end, said bore being adapted to slidably receive said expendable cartridge, means limiting the depth of insertion of said expendable cartridge into said bore, the forward portion of said bore having the approximate configuration and dimensions of the tapered portion of the body members within regular manufacturing tolerances, and a chamber relief means at the rear of said bearing surface adjacent at least in part to the propellant cavity and extending toward the rear end of the body member, said chamber relief means comprising an excessive space between the body member and the bore so that upon firing, the body member does not grip the bore with the same intensity in the excessive space area as it would ordinarily if the normal tolerances were observed, and the cartridge case then buckles inwardly to follow the projectile means out of the gun barrel. i

10. In combination with a plastic expendable cartridge case having a tubular body member open-ended at both ends and having a transverse wall member integrally formed therewith to form a projectile cavity at the front of the body member and a propellant cavity at the rear of the body member, projectile means mounted in said projectile cavity and propellant means and priming means mounted in said propellant cavity, a gun chambercomprising a bore which opens into a receiver means at one end and into an axially aligned barrel at the other end, said bore being adapted to slidably receive said expendable cartridge, means limiting the depth of insertion of said expendable cartridge into said bore, said bore being expanded at its breech end for at least a portion of its length, said expanded bore portion adapted to permit the expendable case, upon firing, to deform outwardly therein thus decreasing the force with which the cartridge case grips the wall of the chamber, the brief time for case expansion into the expanded base portion being sufficient to permit the projectile means to be expelled from the cartridge case whereupon the cartridge case then buckles inwardly to follow the projectile means out of the gun barrel.

11. The combination recited in claim 10 wherein said tubular body member has an outwardly projecting flange means at the breech end thereof, said expanded bore having a diameter slightly greater than said flange means and substantially greater than the major portion of the body member, shoulder means on said flange means longitudinally spaced from corresponding shoulder means on said bore, said shoulder means having an inclined surface means to facilitate inward buckling ofsaid body member upon firing'and said body member being explosively projected forwardly against the gun chamber.

12. In combination with a plastic expendable cartridge case having a tubular body member which is open-ended at both ends and has a transverse wall member integrally formed therewith to form a projectile cavity at the front of the body member where the diameter is greatest and extending rear wardly thereof, the outer surface of said body member tapering forwardly from said point to the front of said cartridge case to form a relatively thin mouth, means in said gun chamber to engage said mouth to limit the depth of insertion of said cartridge case into said bore, the portion of said bore forwardly of said bearing means being of a different configuration than the forward ta ere d cartrid e portion thus defininga free expansion cham er into whic the expendable cartridge case can deform upon firing within said free expansion chamber until the projectile means enters the gun barrel after which time the cartridge case is expelled through the barrel behind the projectile means.

13. In combination with a plastic expendable cartridge case having a tubular body portion open at its rear end and closed at its front end by a transverse wall member to define a propellant cavity therewith, propellant means and priming means secured in said propellant cavity, bearing means at the forward end of said tubular body portion adjacent to said transverse wall member, a tapered body portion having its outer peripheral surface extending forwardly and inwardly from said bearing means to a mouth end, a projectile cavity formed in said tapered body portion and open-ended at said mouth end, projectile means mounted in said projectile cavity and extending forwardly thereof, a gun chamber comprising a bore whose rear end opens into a receiver means and whose forward end opens into an axially aligned barrel, said bore being adapted to slidably receive said cartridge and having a portion thereof in close association with said cartridge bearing means to provide bearing support thereto, means engaging the mouth end of said cartridge to limit insertion of said cartridge in said gun chamber, a free expansion chamber formed forwardly of said cartridge bearing means and said gun bearing support means defined by the outer peripheral surface of the tapered cartridge body portion and the wall of the bore extending forwardly from the gun bearing support means, said forwardly extending gun bore wall being angularly displaced from said outer peripheral surface of said tapered body portion thus forming said free expansion chamber into which the expendable cartridge can move upon firing, said cartridge case then buckling inwardly to be expelled through the barrel behind the projectile. v 14. The combination as recited in claim 13 having a relieved chamber means which facilitates expulsion of said expendable cartridge from the gun barrel after firing, said relieved chamber means comprising an expansion chamber located rearwardly of said cartridge bearing means and said gun bearing support means between portions of the outer periphery of said cartridge case and said bore.

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