US3088405A

US3088405A - Plastic cartridge case

Info

Publication number: US3088405A
Application number: US19336A
Authority: US
Inventors: Jr Homer E Clark
Original assignee: Alcan Co Inc
Current assignee: Alcan Co Inc
Priority date: 1960-04-01
Filing date: 1960-04-01
Publication date: 1963-05-07
Anticipated expiration: 1980-05-07

Description

May 7, 1963 H. E. CLARK, JR

PLASTIC CARTRIDGE CASE Filed A ril 1, 19 60 FIG.6

FIG.4

FIG.2

INVENTOR. HOMER E.C|.A| RK, JR. BY QQQA W M ATTORNEY May 7, 1963 H. E. CLARK, JR

PLASTIC CARTRIDGE CASE 2 Sheets-Sheet 2 Filed April 1, 1960 INVENTOR. HOMER E.CLARK, JR. BY @1 1 w. @144 ATTORNEY 3,088,405 Patented May 7, 1963 3,088,405 PLASTIC CARTRIDGE CASE Homer E. Clark, In, Alton, llllL, assignor to Alcan Company, Incorporated, Alton, IlL, a corporation of Illinois Filed Apr. 1, 1960, Ser'. No. 19,336 3 Claims. (Cl. 1ti243) This invention relates in general to ammunition and, more particularly, to cartridge cases made of plastic.

It is an object of the present invention to provide a cartridge case made entirely of molded plastic and uniquely constructed for primer support to assure reliable firing upon impact of the firing pin. Heretofore, plastic cartridge cases with normal wall thickness have not performed satisfactorily as a lack of proper primer support has caused consistent misfiring and, hence, rendered cases of such material inadequate for desired serviceability.

It is a further object of the present invention to provide a plastic cartridge case having a primer support which permits of minimum plastic in the base thereof, uniformity of wall thicknes, and which is adapted for loading without compression or development of static pressures so that outwardly directed bulge-forming forces on the case are obviated.

It is an additional object of the prevent invention to provide an all plastic cartridge case having a primer reinforcement and which incorporates a wad or bullet support to maintain same in predetermined spaced relationship to the primer.

It is an another object of the present invention to provide an all plastic cartridge case adapted for base loading having a primer support insert, and being adapted for adjusting the case capacity whereby the same may be variably loaded to permit of modifications in the shot charge, the powder charge, etc., in accordance with the type of ammunition desired.

It is a further object of the present invention to provide a plastic cartridge case which may be most economically manufactured; which in practice is productive of positive, reliable firing; which does not require any compression of the charge; and which is productive of a pattern or dispersal with relatively little shot distortion.

Other objects and details of the invention will be apparent from the following description, when read in connection with the accompanying drawings (two sheets) wherein:

FIGURE 1 is a longitudinal, transverse, sectional view of a plastic cartridge case constructed in accordance with and embodying the present invention.

FIGURE 2 is a horizontal transverse section taken on the line 22 of FIGURE 1.

FIGURE 3 is a longitudinal transverse section of another form of plastic cartridge case constructed in accordance with and embodying the present invention.

FIGURE 4 is a horizontal transverse section taken along the line 44 of FIGURE 3.

FIGURE 5 is a longitudinal transverse sectional view of another form of plastic cartridge case constructed in accordance with and embodying the present invention.

FIGURE 6 is a horizontal transverse section taken along the line 66 of FIGURE 5.

FIGURE 7 is a longitudinal transverse section of a further form of the present invention.

FIGURE 8 is a horizontal transverse section taken along the line 88 of FIGURE 7.

FIGURE 9 is a longitudinal transverse section of another form of the present invention.

FIGURE 10 is a horizontal transverse section taken on the line 10-10 of FIGURE 9'.

FIGURE 11 is an exploded view, in partial section, of another form of cartridge case constructed in accordance with and embodying the present invention.

FIGURE 12 is a horizontal transverse section taken along the line 12-12 of FIGURE 11.

FIGURE 13 is an end view of the cartridge case shown in FIGURE 11, taken on the line 13-13 thereof.

Referring now by reference characters to the drawings which illustrate practical embodiments of the present invention, in FIGURE 1, 1 designates a cartridge or shot shell case formed of a molded, suitable plastic, such as polyethylene, polycarbonate, etc., being of traditional tubular character with its normally upper end open for loading purposes and having an integrally formed 'base or head 2 with the customary base flange 3'. Base 2 is centrally provided with an axial bore presenting a primer pocket 4 which projects above the base end wall 5 and incorporates a diametrally increased end portion, as at 6, for engaging the base rim of a primer (not shown). Radiating outwardly from the wall of primer pocket 4 is a plurality of circumferentially spaced ribs or buttresses 7 which are integral on their inner, base, and outer portions with primer pocket 4, the inner face of end wall 5, and the inner side wall of case ll, respectively. Said ribs 7 are of decreasing cross section, being upwardly and outwardly inclined along their upper edge and are of such extent as to project forwardly from primer pocket 4 so that the area of contact or unification with the wall of case 1 is relatively greater than that with the primer pocket wall. Through the decreasing cross sectional charactor of said ribs 7 the portion of case 1 adjacent and above primer pocket 4, normally adapted for receiving the powder or propellant charge, is quite suflicient for such purpose. It will thus be seen that ribs 7 oifer strong lateral support for the primer (not shown) received within the primer pocket 4 so that the latter is provided with suitable resistance upon impact of the hammer, with resultant reliability of firing and consequent uniform explosion and burning of the powder charge. The present invention, thus, presents a greatly improved cartridge which may be most economically manufactured, as the same may be produced from molded plastic having uniform wall thickness and does not require a metal base, thickening of the plastic, or the like, for presenting the primer in adequate resistance to the firing pin. With the present unique rib construction positive firing is assured.

In FIGURE 3, 11 designates a molded plastic cartridge case having an integrally formed head 12, base flange 13, primer pocket 14-, base end wall 15, primer rim receptacle 16, all being identical in construction with the corresponding elements of case 1 above described. Projecting radially from primer pocket 14 for extension between same and the inner wall surface of case 11 is a plurality of circumferentially spaced ribs I7 of decreasing cross section which extend forwardly of primer pocket 14 so that the area of merger of the same on their outer surfaces with the wall of case 11 is greater than that on their inner surface with the outer Wall of primer pocket 14. Said ribs 17 are thus essentially similar to ribs 7 of case 1 as above described, but differs therefrom in that at their upper ends the same are cut away to provide planar surfaces 18 which are mutually aligned and are parallel to the end wall 15; said surfaces 18 cooperate to present a support for a conventional card or obturating wad, as indicated at 19. Thus, in this form of the invention, ribs 17 serve the same primer support function as ribs 7 of case 1 and in addition thereto present a positive support for a wad so as to prevent the latter from being directly supported upon the powder charge and thereby developing an undesired static pressure within case 11. It has been discovered that the failure to inhibit compression within plastic cartridge cases has caused the same to bulge resulting in an undesired increase in diameter causing the shell to be too large to enter gun chamber. In passing, it may be noted that the support surface composed of end faces 18 could be readily used for bullet support as in pistol cartridges.

Referring now to FIGURES and 6, 21 designates a molded plastic cartridge case incorporating an integrally formed base or head 22 with projecting base flange 23; said base 22 is provided with an axial bore forming a primer pocket 24; and with its upper end face 25 forming a gas sealing lip against the primer, spacedly above the outer end wall 26. Primer pocket 24 extends from the upper face 25 to end wall 26. Projecting upwardly from said base end wall 26, radially outwardly of primer pocket 24 and arranged at suitable intervals, but being illustrated at 90 degree intervals, circumferentially of the inner wall of casing 21, are axially extending ribs 27 the outer side edge portion of which merge into or are integrated with the inner wall of casing 21 and with the opposed or inner side edges thereof being free. At their upper ends each rib 27 is continuous with a horizontal, perpendicular portion 27 which extends transversely of casing 21 for mutual intersection at a point centrally of casing 21 in alignment with the axis of primer pocket 24, being spaced thereabove. It may be observed that transverse or horizontal rib sections 27' coact to form a support surface for a wad or bullet (not shown) to locate and maintain same spacedly from the primer and hence prevent compression of the powder. Furthermore, said ribs 27 reinforce the wall of casing 21 and prevents case bulging from the incorporation of a customarily relatively heavy bullet.

Directing attention now to FIGURES 7 and 8, there will be seen a plastic cartridge case 31 embodying a base or head 32 with a base flange 33. Centrally of base 32 there is provided an elongated tubular section indicated at 34, the lower portion of which, being adapted to receive a primer (not shown), forms a primer pocket 35, and which extends upwardly thereof to define the lower portion 36 of the powder chamber, and which terminates in continuity with an upper, annular outward flaring end Wall 37. Said end wall 37 in its outer peripheral portion is integral, or merges, with the inner wall of case 31. The upper, increasing cross sectional region 36 of tubular section 34 forms a compartment for powder to present same in immediate contact with the primer lodged within primer pocket 35. Projecting radially from the outer face of tubular section 34 and extending between same and the confronting portions of the inner face of case 31 is a plurality of ribs 38, the upper ends of which are integral with the under face of end wall 37 with the lower ends thereof being aligned with the lower end face of tubular section 34. By said ribs 38, tubular section 34 with counter pocket 35 is interconnected with the wall of case 31 whereby a firm, rigid structure is provided having adequate support for the primer to cause consistent firing action. Ribs 38 thus divide the space intervening between tubular section 34 and the case wall into a plurality of open ended cells 39.

As cartridge cases 31 are readily formed through the coaction of cooperating punches, the length of ribs 38 may be relatively reduced or extended by the change of but one of the forming punches. Thus, by means of such rib shortening or elongation, the internal capacity of case 31 may be readily adjusted while maintaining standard overall case length. This attribute renders case 31 adaptable for providing various types of ammunition, as the shot and powder charges may be thereby altered to meet predetermined firing conditions.

In FIGURES 9 and there is shown another form of the present invention which comprises a plastic cartridge case 41 having a base 42, base flange 43, tubular section 44 incorporating a primer pocket 45 and powder compartment 46, substantially identical in character to the corresponding parts of cartridge case 31 immediately described hereinabove. Projecting upwardly from the upper end wall surface 47, in circumferentially spaced relationship, and adjacent the inner face of case 41, is a plurality of short support arms 49 which are integral in their outer lateral portions with the inner wall of case 41, being spaced radially outwardly of the upper end of tubular section 44. The upper ends of arms 49 are planar aligned for the purpose of providing a support for a wad (not shown) or the like so as to maintain spacedly above the primer for avoiding any undesired compression of the charge.

Ribs

48 and 38 of

cartridge cases

41 and 31 respectively buttress the related tubular section and, hence primer pocket, to provide the lateral support for the primer to effect the necessary resistance so that proper firing action will take place at all times.

The form of the invention shown in FIGURES 11, 12 and 13 comprises a molded plastic casing 51 open at its lower or base end, and being closed at its top or upper end for forming a shell closure 52, having a plurality of intersecting scored lines or lines of weakness 53 for ready rupture upon shell firing. Said casing 51 is of constant diameter and at its lower end is provided with a base flange 54.

Having an open base end, case 51 is adapted for base loading, wherein the shell components are fed into said case 51 through the open lower end as opposed to the more customary and generally practiced nose or top end loading. Provided for snug disposition in the lower or base end of case 51 is a cylindrical plastic base element 55 comprising a central tubular section 56 having a bore 56', both extending from end to end of said element 55 and the lower region of said bore is designed to provide a primer pocket 57 with the upper end section forming a powder receptacle, as at 58. At its upper end, base element 55 extends radially outwardly from the proximate end of tubular section 56 into an annular end wall 59 the outer peripheral edges of which are curved slightly upwardly to provide a dished or bowl character; said edge abutting intimately against the inner face of cartridge case 51 upon reception of element 55 therein. Radiating from the outer wall tubular section 56 is a plurality of co-extensive ribs or fins 60, the upper ends of which are integral with the under face of end wall 59. Element 55 incorporates an outer annular wall 61, the outside diameter of which substantially corresponds with the inside diameter of case 51 to assure reliable positioning therein. Said outer wall 61 is concentric with tubular section 56, being spaced therefrom by the extent of ribs 60, the outer end portions of which latter merge into the inner face of said outer wall 61. Projecting outwardly from the lower outer face of wall 61 is circumferential base flange 62 for interfitting reception within an annular recess 63 formed at the lower end of case 51 whereby travel of said element 55 toward the nose of case 51 is prevented upon the blow of the firing pin. Base element 55 is dimensioned for jam fitted, snug reception within the base portion of case 51, and when so received therein forms the base or head. The lower end edges of ribs 60, wall 6 1, and tubular section 56 will be in surface alignment with base flange 54. As the inserted ribs 60 will be directed against the inner face of cartridge case 51 thereby presenting circumferential lateral support to the primer for positive firing thereof.

The base loading feature of case 51 oifers the most important attribute of variable capacity, a desideratum hereto unattainable; as the more conventional paper shells with attached exterior metal heads could not, perforce, be base loaded. By variable capacity is meant the ability to internally adjust the relative quantities of the shell components without changing shell size so that different types of shells may be produced. For example, a relatively greater shot charge may be used for forming a cartridge designed for trap shooting whereby the shot-confining region of the shell may be relatively increased by commensurate reduction in length of base element 55, thereby allowing the additional space requisite for the added charge. Similarly, if there were to be a reduction in the quantity of powder a slightly length wise increased element 55 could be easily used. Case 51 would at all times remain constant. Accordingly, base loaded case 51 is peculiarly amenable for facile internal adjustability while preventing compression of the charge, or any static pressures, and yet providing necessary primer support for reliable firing. The scored closure 52 will obviously fragment in sensitive response to explosion. It will be seen that case 51 and element 55 may be produced of diiferent plastic materials and thereby conduce to greater economy in production. Case 51 may be formed of a soft, pliable yet tough plastic such as ethyl cellulose, while base 55 is preferably produced from a more rigid plastic to provide relative stiflness to ribs 60 for eiiective primer support.

In view of the above, it will thus be seen that the present invention incorporates cartridge cases made entirely of plastic which overcome the inadequacies and deficiencies heretofore considered insurmountable. Proper primer support is provided by the cases of the present invention so that misfiring will no longer be encountered by the use of plastic shells and, accordingly, considerable savings may be provided in production and passed along to the users by relatively lower prices. Furthermore, cases of the present invention have invariably a desired shot pattern and dispersal with minimum distortion. As discussed herein, several forms of the present invention provide for base loading which thus renders the related case adaptable for internal adjustability with standard shell length being maintained.

It should be understood that changes and modifications in the formation, construction, arrangement, and combination of the several parts of the plastic cartridge case may be made and substituted for these herein shown and described without departing from the nature and principle of my invention.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

1. A cartridge case formed of molded plastic comprising a casing of tubular form, one end of said casing having a relatively thickened wall portion to define a head, said head having a primer-pocket-forming aperture coaxial with said casing, a plurality of circumferentially spaced ribs integrally formed with said casing and projecting radially inwardly from the inner surface thereof, said ribs being axially parallel with the longitudinal axis of said casing and having end portions remote from said head, a transverse arm integral with each rib in its end portion remote from said head for extension toward the longitudinal axis of said casing, said arms being merged spacedly from said primer-pocket aperture to form a cartridge component support said ribs reinforcing said casing against outward thrust from the weight of a component supported on said arms.

2. A cartridge case as defined in claim 1 and further characterized by the portions of said ribs proximate said primer-pocket aperture being substantially aligned with the adjacent end thereof, said transverse arms being of substantially like thickness as the associated ribs for development of openings between adjacent arms.

3. A cartridge case as defined in claim 1 and further characterized by there being four ribs at ninety degree intervals about the inner surface of said casing, the distance between diametrally opposed ribs being substantially the same as the diameter of the primer-pocket aperture, and said transverse arms having like thickness as the associated rib for development of openings between adjacent transverse arms.

References Cited in the file of this patent FOREIGN PATENTS 958,334 France Sept. 12, 1949 999,372 France Oct. 3, 1951 999,458 France Oct. 3, 1951 1,105,279 France June 29, 1955

Claims

1. A CARTRIDGE CASE FORMED OF MOLDED PLASTIC COMPRISING A CASING OF TUBULAR FORM, ONE END OF SAID CASING HAVING A RELATIVELY THICKENED WALL PORTION TO DEFINE A HEAD SAID HEAD HAVING A PRIMER-POCKET-FORMING APERTURE COAXIAL WITH SAID CASING, A PLURALITY OF CIRCUMFERENTIALLY SPACED RIBS INTEGRALLY FORMED WITH SAID CASING AND PROJECTING RADIALLY INWARDLY FROM THE INNER SURFACE THEREOF, SAID RIBS BEING AXIALLY PARALLEL WITH THE LONGITUDINAL AXIS OF SAID CASING AND HAVING END PORTIONS REMOTE FROM SAID HEAD, TRANSVERSE ARM INTEGRAL WITH EACH RIB IN ITS END PORTION REMOTE FROM SAID HEAD FOR EXTENSION TOWARD THE LONGITUDINAL AXIS OF SAID CASING, SAID ARMS BEING MERGED SPACEDLY FROM SAID PRIMER-POCKET APERTURE TO FROM A CARTRIDGE COMPONENT SUPPORT SAID RIBS REINFORCING SAID CASING AGAINST OUTWARD THRUST FROM THE WEIGHT OF A COMPONENT SUPPORTED ON SAID ARMS.