US3614929A - Plastic shotgun shell - Google Patents

Abstract

AN ALL PLASTIC SHOTGUN SHELL COMPRISED OF A TUBULAR PLASTIC CASING HAVING AN INTEGRAL BASE WALL WITH AN APERTURE THEREIN THROUGH WHICH A PRIMER EXTENDS, A PLASTIC OVER-SHOT WAD CLOSING THE END OF SAID TUBULAR CASING OPPOSITE SAID BASE WALL, A ONE-PIECE PLASTIC SHOT CUP AND OVER-POWDER WAD UNIT WITHIN THE TUBULAR CASING, AND A PLASTIC BASE WAD SEATED WITHIN SAID CASING AGAINST SAID BASE WALL. THERE IS A NON-BINDING FIT BETWEEN THE PRIMER AND THE APERTURE IN THE CASING BASE WALL, THE PRIMER BEING FIRMLY GRIPPED AND

HELD IN PLACE BY MEANS OF A FORCE FIT BETWEEN THE PRIMER AND AN AXIAL POCKET FORMED WITHIN THE YIELDABLE BASE WAD INTO WHICH THE PRIMER EXTENDS.

Description

Oct. 26, 1971 R R ETAL 3,614,929

PLASTIC SHOTGUN SHELL Filed April 21, 1969 INV/i/V'I'UR. 40 64 5'9 58 62 2 GEORGE L. Alt/e752 BY GLE/V 4. m/rrasrzoar W *M Arron/Er:

United States Patent Olfice 3,614,929 Patented Oct. 26, 1971 3,614,929 PLASTIC SHOTGUN SHELL George L. Herter and Glen L. Mittelsteadt, Waseca, lVIinn., assignors to Herters, Inc., Waseca, Minn. Filed Apr. 21, 1969, Ser. No. 817,860 Int. Cl. F42b 7/06, 7/08 US. Cl. 10243 P 6 Claims ABSTRACT OF THE DISCLOSURE An all plastic shotgun shell comprised of a tubular plastic casing having an integral base wall with an aperture therein through which a primer extends, a plastic over-shot wad closing the end of said tubular casing opposite said base wall, a one-piece plastic shot cup and over-powder wad unit within the tubular casing, and a plastic base wad seated within said casing against said base wall. There is a non-binding fit between the primer and the aperture in the casing base wall, the primer being firmly gripped and held in place by means of a force fit between the primer and an axial pocket formed within the yieldable base wad into which the primer extends.

BRIEF SUMMARY OF THE INVENTION The shotgun shell of this invention is particularly characterized by an all plastic structure which lends itself to relatively simple and inexpensive manufacturing, which is particularly adapted for multiple use and reloading of the several components, and which is specially constructed and arranged so as to eliminate the problem of distorting or rupturing the shell casing at its base end resulting from the pressures generated by an exploding charge detonated within the shell casing.

These basic objectives are realized by a unique design of the base or head end of the plastic shotshell which provides for the retention of a primer in the base wall of the shell in such a way as to prevent the exertion of undue outward force on the casing base wall by the primer as it is detonated. The great radial force transmitted by the primer to the base end of the shell casing upon detonation of the primer and propellant charge has been a major cause of cracking and rupturing of the base end of plastic shotshells. This problem is attributable, in part at least, to the base structure of prior art plastic shotshells wherein'the primer is tightly fitted into a pocket or cavity in the base wall of the shell casing. In accordance with our new plas tic shotshell design, the plastic casing of the shotshell is provided with an integral base wall having an aperture therein through which a primer extends in a relatively loose, free fit therewith. The primer is held in place by a plastic base wad having an axially extending, central cavity within which the primer is tightly fitted so as to be retained in the desired position. The shock and pressure transmitted by the detonating primer is absorbed almost entirely by the plastic base wad, which is formed from yieldable and resilient plastic material, thereby preventing the transmission of potentionally damaging forces and shock waves to the lower end of the shell casing and its base wall.

As a particularly advantageous feature of our improved plastic shotshell, we utilize a plurality of axially spaced rings projecting inwardly from the interior surface of the aforesaid central cavity in the base wad to grip the primer and firmly hold it in place. As the base wad deforms under the pressure exerted by the exploding propellant charge within the shell casing, the rings on the base wad cavity are forced inwardly in tight, sealing engagement with the primer so as to prevent the leakage of combustion gases downwardly around the primer. Peripheral sealing teeth on the external surface of the base wad tightly engage the interior wall surface of the shell casing so as to preclude the leakage of gases between the base wad and the plastic casing.

A further beneficial feature of our improved plastic shotshell resides in the use of an annular groove in the top surface of the base wad, the downward fiow of combustion gases into said groove on detonation of the propellent charge causing the opposed side walls of said groove to be forced apart, thereby assisting in moving said sealing rings and teeth into tight engagement with the primer and the plastic casing respectively.

In addition to the aforesaid plastic casing and base wad, the all plastic shell structure further includes a plastic shot cup and over-powder wad of unitary construction and a top closure wad which is preferably formed from the same relatively soft, plastic material as the base wad.

These and other objects and advantages of our invention will become readily apparent as the following description is read in conjunction with the accompanying drawings wherein like reference numerals have been used to designate like elements throughout the several views.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical section view showing the all plastic shotshell of this invention;

FIG. 2 is a top view of the shell of FIG. 1 showing the top, closure wad;

FIG. 3 is a fragmentary, vertical section view showing the lower end of the shell of FIG. 1 and the shape of the base wad upon detonation;

FIG. 4 is a top plan view of the base wad of this invention;

FIG. 5 is an elevation view, partially in section, of the base Wad; and

FIG. 6 is a bottom plan view of the base wad of FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, we have shown in FIG. 1 a preferred embodiment of our improved, all plastic shotgun shell utilizing a tubular casing 1 having an integral base wall 2 at one end thereof. Casing 1 is preferably molded from relatively hard plastic material such as polycarbonate, base wall 2 being formed integrally with casing 1 during the molding operation so as to thereby provide a one-piece casing and base wall unit. By molding base wall 2 integrally with casing 1, we have simplified the manufacturing procedure by eliminating the need for gluing, welding or otherwise bonding a closure base to the head or base end of tubular casing 1. A peripheral flange 4 on base wall 2 serves as a contact element for an ejection mechanism in a shotgun.

Disposed within casing 1 is a shot cup 6 which contains a plurality of shot pellets 8, and which preferably comprises one portion of a unitary shot cup and overpowder wad element designated generally by reference numeral 10. Unitary element 10 is molded from pliable and yieldable plastic such as polyethylene, and includes a transversely extending overpowder wad 12 at its bottom end. Depending from over-powder wad 12 is a powder enclosing and sealing skirt 14 comprised of inner and outer annular walls 15 and 16. A plurality of spacing and sealing discs or rings 18 extend transversely outwardly from center post 20 of unitary over-powder wad and shot cup and bear against the inside surface of tubular casing 1 at their outer ends. Central post 20 of element 10 is axially compressible to thereby provide a shock absorbing and cushioning effect to assist in absorbing the pressures generated by the detonation of a propellent charge 22 contained under over-powder wad 12.

The open, upper end of tubular casing 1 is closed by means of a top closure wad 24 which is also molded from soft, yieldable polyethylene plastic. Closure wad 24 is comprised of a relatively thin, transversely extending central section 26 and a peripheral rim 28. The necessary strength is imparted to central section 26 by means of a plurality of radially extending ribs 30 which extend along both the upper and lower surfaces of wall section 26. The radial orientation of strengthening ribs 30 is shown in FIG. 2. Peripheral ring section 28 is beveled around its outer periphery on both the upper and lower faces thereof, the beveled surfaces being indicated at 32 and 33 in FIG. 1. The underside of top closure wad 24 bears against the top end of shot cup 6 and shot pellets 8, and it is held in contact therewith by inwardly crimped upper end portion 34 of tubular casing 1 in the manner shown in FIGS. 1 and 2. Crimped end portion 34 of easing 1 is turned inwardly at a slight angle to conform to the angle of beveled surfaces 32 and 33 of closure wad 24. The provision of beveled surfaces 32 and 33 and strengthening ribs 30 on both the upper and lower faces of closure wad 24 renders wad 24 reversible so as to eliminate the need for orienting it with a particular face directed upwardly during the assembly of the shotgun shell.

The remaining element of our all plastic shotgun shell is a functionally important base wad designated by reference numeral 36. Base wad 36 is formed from soft, yieldable plastic preferably polyethylene, and is of generally cylindrical configuration as is shown in FIGS. 4, 5 and 6. The bottom surface 38 of base wad 36 is substantially flat and planar so as to seat flush against flat inner surface 40 of base wall 2 when base wad 36 is inserted into the base or head end of tubular casing 1 in the position shown in FIG. 1.

At its lower end, base wad 36 has a substantially conical outer wall surface 42 which nests within and conforms to inner conical wall surface 44 at the lower end of tubular casing 1. A plurality of longitudinally spaced rings 44 are provided around the outer periphery of base wad 36 at its upper end, rings 36 terminating at relatively sharp edges 45 to thereby define a plurality of spaced teeth in vertical cross-section as shown in FIGS. 1 and 5. Edge portions 45 of rings 44 engage the inner wall surface of tubular casing 1 and assist in holding base wad 36 in place. The upper end of base wad 36 is dished inwardly and is defined by concave top wall 46 which cooperates with over-powder Wad 12 to form the space within which propellent charge 22 is contained. Relatively thin wall section 48 at the upper end of base wad 36 between top wall 46 thereof and the outer peripheral surface of wad 36 is readily compressible and deformable, thereby rendering base wad 36 particularly effective as a cushioning and shock absorbing device.

Extending axially of base wad 36 and disposed substantially centrally thereof is a tubular cavity or pocket 50 within which a primeris received and retained in a manner hereinafter described. The upper end of primer cavity 50 communicates with the powder containing space above top wall 46 of base wad 36 through a reduced diameter flash passage 52. The smaller diameter of flash passage 52 compared to the diameter of tubular cavity 5i) provides a shoulder 54 against which the upper end of a primer abuts. The primer gripping and retaining function of cavity 50 may be improved by providing a plurality of longitudinally spaced rings 56 along the surface thereof. Rings 56 project radially inwardly from the wall surface of cavity 50 and are sized to tightly grip a primer 58 shown in place in FIG. 1. Base wad 36 further includes an annular groove 60 formed within upper wall 46 thereof between flash passage 52 and the peripheral surface of wad 36. Groove 60 serves a dual function as both a means of reshaping base wad 36 as required after use and as a pressure transmitting surface in a manner explained below.

Referring again to FIG. 1, it Will be seen that base wall 2 is provided with an aperture 62 through which primer 58 extends. A slightly larger diameter recess 64 in the bottom face of base wall 2 serves as a seat for the rim 59 of primer 58. It is to be noted that base wall 2 has a thickness somewhat greater than that of the vertically extending portion of tubular casing 1 to increase the strength of base 'wall 2 and improve its ability to satisfactorily withstand the shock and pressure generated by the explosion of propellent charge 22. However, it is also to be noted that base wall 2 has a thickness substantially less that the length of primer 58, whereby primer 58 is contained over the greater portion of its length within tubular cavity 50 of base wad 36. Central aperture 52 in base wall 2 is sized so that it has a diameter equal to or slightly greater than the maximum diameter permitted for primer 58 within tolerance limitations. For example, if primer 58 has a maximum diameter of .242 inch, then the minimum diameter of aperture 62 will be .242 inch. By virture of this structural arrangement, primer 58 may be inserted freely through aperture 62 into tubular cavity 50 in a non-binding, relatively loose fit with aperture 62. Primer 58 is actually firmly gripped and held in place by tubular cavity 50 of base wad 36. This is accomplished by sizing the diameter of cavity 50 so that it is significantly less than the diameter of primer 58. Thus, after passing freely through aperture 62 in base wall 2, primer 58 must be forced upwardly into reduced diameter cavity 50. As primer 58 is forced into cavity 50 the yieldable and resilient plastic material of base wad 36 which defines cavity 50 is compressed radially outwardly and then flexes inwardly in tight, gripping engagement with the exterior surface of primer 58. The secure retention of primer 58 within cavity 50 is further insured by rings 56 which are of even smaller diameter than cavity 50 and thus bear against primer 5-8 very tightly. Because primer 58 is firmly gripped and held in place by base wad 36 and is not in tight, friction contact With aperture 62 of base wall 2, the outward forces exerted *by primer 62 when it is struck by a firing hammer and explodes are absorbed almost entirely by yieldable and resilient base wad 36. A very minimum amount of shock and pressure is transmitted to base wall 2, with the result that cracking and deforming of plastic base wall 2 is effectively prevented.

Upon the detonation of primer 58 and the explosion of propellent charge 22, base wad 36 will be deformed and compressed downwardly in the manner shown in FIG. 3. The relatively small thickness of wall section 48 permits upper wall surface 46 of base Wad 36 to be compressed downwardly and radially outwardly to the position shown in FIG. 3 in response to the downward force exerted by the combustion gases within the space between over-powder wad 12 and base wad 36. Teethlike sealing rings 44 will be forced downwardly and pressed together to thereby provide a cushioning and shock absorbing effect as top, concave Wall 46 of base wad 36 is urged downwardly. Due to its concave shape, wall 46 will also receive and transmit force radially outwardly with he result that pointed, peripheral edges 45 of sealing rings 44 will be forced outwardly into tight contact with the inside surface of tubular casing 1. An effective seal will thus be provided along the lower,

inside surface of casing 1 to prevent expanding gases from flowing downwardly between base wad 36 and casing 1 towards base wall 2. The pressure of the combustion gases acting within annular slot 60 of base wad 36 will also cause the side walls of slot 60 to be forced apart in the manner shown in FIG. 3. As the outside side wall 61 of slot 60 moves outwardly it assists in moving peripheral teeth 44 into tight, sealing contact with the inside surface of tubular casing 1. Inside wall 63 of slot 60 will be forced inwardly, thereby assisting in pressing rings 56 of cavity 50 into very tight, sealing engagement with primer 58. The firm contact of resilient, pliable polyethylene rings 56 against primer 58 provides a very tight seal which prevents the leakage of combustion gases downwardly around the outside surface of primer 58. The compression and deformation of polyethylene base wad 36 in the manner described above provides very effectively for the cushioning and absorption of the forces and shock waves generated by the exploding propellent charge with the result that the lower end of relatively hard plastic casing 1, as well as base wall 2, are extremely well protected against deformation or cracking upon detonation of the propellent charge. Moreover, as noted above, since primer 58 is firmly gripped within yieldable base wad 36 and fits relatively loosely within aperture 62 of base wall, 2, the outward forces transmitted from primer 58 when it is detonated are substantially entirely absorbed by yieldable and deformable base wad 36, thereby eliminating the cracking or deformation of base Wall 2 which frequently occurred on prior art plastic shotgun shells having the primer tightly held within an aperture in the plastic base wall.

Polyethylene base wad 36, being resilient as well as yieldable and deformable, will normally return to its original shape after the shotshell in which it is used has been fired. Thus, plastic casing 1 and "base wad 36 may be reloaded and reused a considerable number of times. If primer cavity 50 does expand radially upon detonation of the primer, annular slot 60 in upper wall 46 of base wad 36 may be utilized to compress the walls of cavity 50 back inwardly to their original diameter. This is accomplished by inserting a sleeve or tubular extension on a reloading tool into slot 60 and exerting downward force on base wad 36 as it is pressed into the lower end of tubular casing 1. The downward force exerted by the reloading tool on the bottom of annular groove 60 will compress the lower end of base wad 36 and assist in forcing the side walls of cavity 50 inwardly to their original position.

Although we have shown and described our improved all plastic shotshell with respect to preferred embodiments thereof, those skilled in the art will readily appreciate that various changes could be made in the shotshell design Without loosing the benefits of the particular base wad structure described herein. For example, base wad 36 could be held in place by being wedged into the lower end of casing 1 rather than by using peripheral teeth 44. Also, in lieu of contact rings or teeth 44, a plurality of dimples in the outer surface of base wad 36 could be utilized to hold base wad 36 in the plastic case. Also, although rings 56 on the inside wall surface of primer cavity 50 assist in holding primer 58 in place, they are not essential. As long as the diameter of primer cavity 50 is sized properly so that it is substantially less than the diameter of primer 58, the yieldable plastic walls of cavity 50 will firmly and tightly engage primer 50 and effectively hold it in place after it is forced into cavity 50.

We claim:

1. An all plastic shotshell comprising in combination:

a tubular casing constructed entirely of relatively hard,

polycarbonate plastic, said casing having a tubular case wall and terminating at one end in an integral base wall to provide a one piece casing and base wall unit, said base wall being substantially fiat and of uniform thickness, and having a central aperture sized to permit the insertion of a primer therethrough in a free, non-binding fit therewith, the thickness of said base wall being substantially less than the length of the primer to be inserted therethrough and greater than the thickness of said tubular case wall;

a relatively soft, yieldable plastic closure wad secured Within the opposite end of said tubular casing;

a one-piece plastic shot cup and over-powder wad unit disposed within said tubular casing; and

a base wad of relatively soft, yieldable plastic material positioned within said casing in abutting contact with the inside surface of said base wall and defining with said over-powder wad a space for a propellent charge, said base wad having an elongated, central cavity in alignment with said aperture in said base wall and sized to engage a primer inserted therein in firm, gripping contact therewith.

2. A shotshell as defined in claim 1 wherein:

said closure wad has a beveled surface extending circumferentially around its outer periphery and is held in place by a short, inwardly crimped portion of said opposite end of said tubular casing which bears against said beveled surface of said closure wad in conforming engagement therewith.

3. A shotshell as defined in claim 1 and further including:

a primer received within said central cavity of said base wad and extending through said central aperture in said base wall, said aperture in said base wall being of equal or greater diameter than said primer inserted therethrough, and said central cavity in said base wad having a diameter slightly less than that of said primer received therein, whereby said primer extends through said base wall aperture in a free, non-binding fit therewith and is received in a force fit with said central cavity of said yieldable, plastic base wad so as to be tightly engaged and retained by the walls of said base wad cavity.

4. A shotshell as defined in claim 1 wherein:

a plurality of longitudinally spaced rings project inwardly from the wall surface of said base wad cavity, said rings being sized to tightly grip said primer and thereby assist in holding it in place; and

said base wad includes an annular groove in the upper surface thereof between said central cavity and the outer periphery of said base wad, the downward flow of pressurized combustion gases into said groove upon detonation of said propellent charge causing the opposed side walls of said groove to be forced apart, thereby forcing said rings on said central cavity into tight, sealing engagement with a primer contained Within said cavity.

5. A shotshell as defined in claim. 4 wherein:

said base wad further includes a plurality of longitudinally spaced, circumferentially extending sealing teeth on its peripheral surface, said teeth being in contact with the inside surface of said tubular casing and being forced into sealing engagement therewith as said base wad deforms in response to the pressure generated by the detonation of said propellent charge.

6. An empty, primed shotgun shell to be assembled with shot and powder charges into a shotshell, comprising:

a tubular casing constructed entirely of relatively hard unyielding plastic, said casing having a tubular case wall and a transverse base wall formed integrally with each other in a single, one piece construction, said base wall having substantially fiat inner and outer surfaces and a substantially uniform thickness across the entire width thereof, said base wall further having a central aperture therein to accept a primer therein in a non-binding fit;

said aperture having a counterbore adjacent the outer surface of the base wall to define a depressed ledge References Cited adjacent the outer surface; UNITED STATES PATENTS a primer projecting into and through said aperture in the base Wall in a non-binding relationship to 3298313 1/1967 Comerford 1O242 c the periphery of the aperture, said primer having a 5 3,359,906 12/1967 Herter 1O295 peripheral bead seated on said ledge; 3,517,617 1/1970 Han 10242 and a base wad of relatively soft yieldable plastic ma- FOREIGN PATENTS terial positioned Within said casing in abutting con- 1,294,551 4/1962 France 102-43 tact with the inner periphery of the tubular case Wall, said base Wad further having a substantially 10 flat bottom surface bearing against the inner sur- ROBERT STAHL Pnmary Examiner face of said base Wall over substantially the entire width thereof, and an elongated central cavity aligned with the aperture in the base Wall and re- 10243 C, 95; 112-44 ceiving and tightly gripping the primer and retain- 1 ing the primer in a stationary position.

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