US3628225A

US3628225A - Method of making a military blank cartridge

Info

Publication number: US3628225A
Application number: US746071A
Authority: US
Inventors: Robert W Parker
Original assignee: Individual
Current assignee: Individual
Priority date: 1968-07-19
Filing date: 1968-07-19
Publication date: 1971-12-21
Anticipated expiration: 1988-12-21

Abstract

A blank cartridge for use in military rifles and machine guns, such cartridge having a metal-coated plastic body the nose of which is swaged into an elongated tapered configuration after the body is loaded. An apertured gas-seal and metering element is mounted between the nose and the base, the latter being locked to the cartridge body by a locking and sealing insert. In accordance with the method, the body is a metal-coated plastic extrusion which is first locked to the base, then loaded with powder, and then swaged to form the elongated tapered nose portion.

Description

Unite States Patent [72] Inventor Robert W. Parker 668 N. Hart, Orange, Calif. 92767 [2!] Appl. No. 746,071 [22] Filed July 19, 1968 [45] Patented Dec. 21,1971

[54] METHOD OF MAKING A MILITARY BLANK CARTRIDGE 19 Claims, 16 Drawing Figs.

[52] US. Cl 29/l.3, 86/ 10, 102/42, 264/292 [51] Int. Cl 521d 51/54 [50] Field of Search 29/13; 86/10, 25, 39, 47; 102/42, 43, 264/292, 328

[56] References Cited UNITED STATES PATENTS 2,591,286 4/1952 Paulve 86/10 2,682,222 6/1954 Richardson et al.. 86/39 X 3,027,621 4/1962 Clark, Jr... 29/1,} 7

3,176,614 4/1965 Woodring 102/43 3,227,085 1/1966 Rarner 102/42 3,349,459 10/1967 King et al... 29/].3 3,363,296 1/1968 Duffield 29/1 .3 3,408,718 11/1968 Weaver 2 /13 Primary Examiner-John F. Campbell Assistant Examiner-Robert T. Craig AtlorneyGausewitz & Carr ABSTRACT: A blank cartridge for use in military rifles and machine guns, such cartridge having a metal-coated plastic body the nose of which is swaged into an elongated tapered configuration after the body is loaded. An apertured gas-seal and metering element is mounted between the nose and the base, the latter being locked to the cartridge body by a locking and sealing insert. In accordance with the method, the body is a metal-coated plastic extrusion which is first locked to the base, then loaded with powder, and then swaged to form the elongated tapered nose portion.

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SHEET 2 [IF 4 F a m INVENTOR. LL- Rosaer W PARKE/Q firrae/ws s METHOD OF MAKING A MILITARY BLANK CARTRIDGE BACKGROUND OF THE INVENTION 1. Field of the Invention The field is that of military blank cartridges which must be capable of withstanding extreme heat and cold, and be capable of generating high gas pressures in order to operate the automatic weapons, yet should be extremely inexpensive and formed of nonstrategic materials.

2. Description of the Prior Art It has long been sought to create a military blank cartridge formed of plastic, yet which will not jam or otherwise misfunction under various conditions including relatively extreme heat and cold. Another major requirement is that the blank cartridge will not disintegrate and project dangerous portions out of the barrel of the weapon where they may cause injury to persons or property, or may start fires. Other major requirements include economy of manufacture with nonstrategic materials.

Military and other blank cartridges formed of plastic are conventionally injection molded, but this creates severe problems in several areas not only relative to cost but also relative to the fact that nose end portions of the injectionmolded cartridges may blow off and cause injury to persons in the vicinity of the weapon. Furthermore, it is difficult or expensive to provide an adequate means for connecting the base to the end of the injection-molded cartridge body. Such bases are conventionally expensive, being formed on screw machines or lathes, as distinguished from being economical stamped elements.

The characteristics of prior art military blank cartridges formed of plastic are such that they frequently jam or otherwise malfunction in the automatic weapons in which they are employed. In this connection, it is pointed out that the temperatures of the breech portions of the weapons frequently rise to high levels, which may deteriorate the plastic and thus cause jamming. Conversely, the weapons are sometimes used in very cold climates, producing the above and other forms of malfunction. A representative blank cartridge formed of plastic is shown by U.S. Pat. No. 2,918,868 for Cartridge.

A considerable amount of art exists in the field of shotgun shells, representative U.S. Pat. being No. 3,099,958 for Firearm Cartridges, No. 3,162,124 for Plastic Cartridge, and No. 3,215,075 for Shotshell. These and other shotgun shells are injection molded and incorporate crimped end portions adapted to retain the shot in the cartridge. To the best of applicant's knowledge, such shells are not necked down, by swaging or otherwise, nor are they metal-coated.

SUMMARY OF THE INVENTION Applicant has discovered that a metal-coated plastic extrusion, which is necked down by swaging to provide the tapered and elongated nose needed for feeding purposes, will not create substantial jamming problems in the automatic weapon despite severe temperature conditions. In addition, and very importantly, applicant provides a relationship such that no portion of the blank cartridge is projected out the barrel of the weapon where it may cause injury or start fires. Furthermore, the blank cartridge is strongly and economically constructed of plastic, aluminum and other readily available and nonstrategic materials. Novel wad means are provided (for locking, metering and other purposes) and are assembled by highly effective and novel methods.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is an enlarged longitudinal sectional view of a military blank cartridge constructed in accordance with the present invention, prior to firing thereof, a metal coating thereon being unshown in this and all views excepting FIGS. 3 and 3A;

FIG. 3 is a horizontal sectional view taken on line 3-3 of FIG. 2, and illustrating a metal coating on the plastic surfaces;

FIG. 3A is a greatly enlarged view illustrating fragmentarily one portion of the wall, and showing a plurality of metal coatings thereon;

FIG. 4 is a schematic view illustrating the loading, swaging and crimping steps performed during manufacture of the blank cartridge;

FIG. 5 is an enlarged sectional view on line 5-5 of FIG. 4;

FIGS. 6-13 are longitudinal sectional views respectively corresponding to the eight stations of the apparatus of FIG. 4;

FIG. 14 is an elevational view illustrating one of the stations of the apparatus of FIG. 4; and

FIG. 15 is a schematic block diagram illustrating the manner of metal coating the plastic cartridge body.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS Referring first to FIG. 1, the military blank cartridge is illustrated to comprise an elongated plastic case 10 having a powder-containing body 11 and an elongated tapered nose 12, the latter terminating in a crimp-folded conical evanescent closure 13. The region of case 10 between nose l2 and body 1 l is shouldered, relatively sharply tapered, as indicated at 14.

The blank cartridge additionally comprises a gas-metering wad 16, a powder-sealing'wad or bulkhead 17, a locking and gas-sealing wad 18, and a stamped metal base I9 containing a suitable primer 20. The powder in the blank cartridge is indicated at 21 as being contained in the chamber 22 which is defined between bulkhead l7 and wad 18, the great bulk of the powder being contained between gas-metering wad l6 and locking and gas-sealing wad l8.

Stated more specifically, the plastic case 10 is formed by swage-reducing a tubular extrusion as will be described hereinafter. The body 11 of the cartridge case is forwardly tapered slightly (converging toward nose I2), whereas the shoulder 14 is forwardly convergent (frustoconical) to a much greater degree. Tapered nose 12 is shown as being forwardly convergent and frustoconical, the angle of taper being substantially less than that of shoulder 14 but substantially more than that of body 11. The conical nose closure 13 is sharply tapered and forms an evanescent closure adapted to be blown open, but without resulting in discharge of any case material out of the weapon, as illustrated at 24 in FIG. 2.

The gas-metering wad I6 is formed of a suitable gas-impervious material, such as linear polyethylene, having formed therethrough an axial metering passage 25 which (in the illustrated embodiment) communicates with a counterbore 26 at the downstream end thereof. The downstream or front end of metering wad 16 is shown as being located adjacent the junction between nose l2 and shoulder 14, but it is pointed out that in some forms of the invention the metering wad may initially be mounted much closer to base 19 and then gas-shifted upon firing of the cartridge to the position illustrated in FIGS. 1 and 2.

The peripheral wall of metering wad 16 has a front portion which tapers correspondingly to the taper of shoulder 14 so that such elements will be in surface engagement as illustrated. correspondingly, the rear portion of wad l6 tapers only slightly, corresponding to the portion of body 11 which is relatively adjacent shoulder 14. The rear surface 27 of wad I6 is shown as being frustoconical and forwardly convergent, this permitting radial-outward flexing of the rear wad portion into gas-sealing engagement with body 11 upon firing of the car tridge.

The powder-enclosing or sealing wad or bulkhead I7 is seated on the forward surface of metering wad I6, being formed of a material which will not create any damage or injury, or start fires, in response to projection of components thereof out of the weapon in which the cartridge is fired. More specifically, wad 17 is preferably formed of expanded beads of polystyrene as specified in U.S. Pat. No. 3,354,571 for Blank- Cartridge Gun and Cartridge Therefor. The wad l7 prevents passage of any powder 21 out through the passage 25 and counterbore 26, so that the powder remains in a relatively compact mass and so that the nose 12 remains empty. It is emphasized that there is nothing between wad 17 and the evanescent nose closure 13. Accordingly, the only things which pass out of the gun are the products of combustion of powder 21, and the minute disintegrated particles of the wad l7.

Locking and gas-sealing wad 18 may be formed of a suitable plastic, such as linear polyethylene, being force-fit into body 1 1 adjacent base 19. The fit is caused to be sufficiently tight to insure that there is locking engagement between base 19 and the rear end of cartridge body 1 l, and also sufficiently tight to prevent escape of any gas through the interface between the base and the cartridge body. The locking and gas-sealing wad 18 may perform this locking and sealing function, even with a base 19 which is stamped and thus extremely inexpensive to manufacture, because of the fact that the wad may be introduced into the cartridge body 11 prior to swage-reduction of the cartridge case.

Formed through wad 18 is an axial passage or port which registers with a central port in the center of base 19 and permits passage of explosive gases from primer 20 into the powder chamber 22. The powder 21 will thus be ignited upon striking of the primer.

The base 19 may be a cup-shaped stamping made of a suitable nonstrategic metal, such as aluminum, having a cylindrical sidewall which is necked inwardly to provide an annular groove 31 adjacent the extractor rim 32. The bottom or rear wall of the base 19 is recessed and apertured to receive primer 20 in press-fit (and preferably staked) relationship.

The type and quantity of powder 21 are selected to generate the gas pressure necessary to properly operate the automatic weapon, and to create the desired sound effects, etc. The diameter of the passage 25 in wad 16 is correlated to the type and quantity of powder in such manner that the pressure buildup in powder chamber 22, in response to ignition of the powder, will be that desired for the particular weapon. Thus, it is possible to change powders by merely changing the diameter of the bore or passage 25, and without changing any other characteristic of the cartridge. However, if lesser quantities of powder are required it may be desired to shift the metering wad 16 toward the base and thus reduce the size of the powder chamber.

Because the cartridge case is swage-reduced from a tubular extrusion, without the necessity of injection molding, it is not only extremely economical to manufacture but also (as indicated above) eliminates prior art problems relative to blowing out of the nose portion of the blank cartridge. In injection-molded cartridge cases, wherein the nose is molded in closed condition but with score lines adapted to permit rupture, it frequently occurs that the score regions are either too thin or too thick. If they are too thin, breakage frequently occurs and permits portions of the cartridge case to blow out and cause injury. On the other hand, if the score regions are too thick there may be excessive pressure developed within the cartridge, resulting in adverse effects including blowback of the base. With the present construction wherein the nose is folded or crimped shut, there are no score regions and there is no danger that portions of the cartridge body will blow out or will refrain from blowing out and thus create adverse pressure conditions.

Cartridge body 11 may be provided with longitudinal ribs and grooves (not shown) in order to facilitate extraction after firing. It is emphasized, however, that extraction is facilitated because of the fact that the plastic from which the body is formed is a type which contracts or shrinks when heated, so that shrinkage occurs after firing. The plastic expands during the period when the cartridge is being fired, due to the presence of gas pressure in chamber 22, but immediately contracts after firing so that extraction is rendered easy. There is, therefore, less danger of jamming, less wear on the chamber wall, and less wear on the extractor mechanism, than in the case of cartridges formed of brass, for example.

In accordance with an important feature of the present invention, extraction is rendered even more certain, and operation under extreme conditions of heat and cold rendered more reliable, by coating the cartridge case 10 with metal. Because of the presence of the metal coating, very little friction is created between the cartridge case and the chamber wall even when the latter is very hot, so that extraction is still possible and no jamming occurs.

Because the metal coating on the cartridge case is thin, it is shown only in FIGS. 3 and 3A, and one method of applying the same is illustrated schematically by block diagram FIG. 15. It is to be understood, however, that the coating may be regarded as present on all of the remaining views.

Referring to FIG. 3, a metal coating 35 is shown as provided on the cartridge body 11, but such coating is also present on the remaining exterior and interior portions of the cartridge case 10. The coating may be a suitable metal, for example nickel, which may be electroplated or otherwise applied onto the cartridge body after preparation thereof as will be described subsequently.

Referring to FIG. 3A, there is shown as present under the exterior coating 35 an interior or preparatory coating 36 adapted to permit electroplating of the exterior coating 35 onto the plastic. One manner of applying the coatings 35 and 36 will be stated hereinafter relative to FIG. 15.

The plastic employed to make the cartridge case 10 is a thermoplastic synthetic resin, which is capable of being swaged to reduce diameters in response to application of low heat and high pressure, and is relatively impervious to the adverse effects of ambient heat and cold. The resin should be rigid, should be capable of receiving a metal coating as described hereinafter or by other processes, and should shrink in response to application of heat.

A preferred resin is a relatively rigid polyolefin, preferably a polyethylene characterized by a high degree of linearity and crystallinity and by a high molecular weight. Such polyethylenes are produced by various processes under relatively low temperatures and low pressures of polymerization using suitable catalysts in admixture. They have high densities and molecular weights, and a high degree of linearity in the polymer chains. They have high softening or melting points and may be classified as rigid polyethylenes.

Stated otherwise, the resin may be a type III polyethylene as described by ASTM (American Society of Testing Materials) specification O-1248. More specifically, the rigid polyethylene employed is Plaskon 6-34," a trademark of Allied Chemical Corporation, and which is a high-density polyethylene produced by the catalytic polymerization of ethylene. Butene-l is present during the polymerization in small amounts. The resulting polymer will have a nominal density of 0.946 gram/cc. using ASTM D 1505. Resin molecular weight is high. When tested by ASTM D 1238, condition F, the melt flow has a nominal value of 3.5 grams/ 10 minutes. Plaskon 6-34" is stabilized with 0.1 percent Santowhite Powder and 0.1 percent dilouryl thiadipropionate.

Resins other than linear polyethylene, and which may be employed in some instances to make the present cartridge case, include styrene butadiene acrylonitrile terpolymer, polypropylene of high isotacticity, ethyl cellulose, and cellulose acetate.

METHOD OF MANUFACTURE Referring first to FIG. 4, a table or support 40 has mounted thereon a stationary backup bar 41 adjacent which is a movable or walking feed element 42. As shown in FIG. 5, the walking element 42 has portions 43 shaped to receive the extractor rim 32, and other portions shaped to fit into annular groove 31 of each cartridge base 19. Thus, the cartridge base is locked in position except when intentionally moved by the element 42.

The relationship is such that the element 42 oscillates back and forth once for each operation of the swaging and assembly apparatus, in such manner that the cartridge bases 19 and connected components move forward from each station to a predetermined adjacent station.

Shown at the extreme left of FIG. 4 is a chute 45 through which passes a prestamped cartridge base 19 having preassembled therewith a primer 20. Upon the next movement of feed element 42, the base 19 from chute 45 passes to the first station, being disposed at a predetermined point beneath a tubeassembling mechanism a portion 46 of which is shown in section in FIG. 6. Portion 46 has formed therein a cylindrical passage 47 the lower end of which is counterbored at 48 to receive the cylindrical wall of base 19. Suitable mechanism, not shown, is provided to move the portion 46 downwardly until the base is partially received in counterbore 48, following which a tube-feeding mechanism is employed to feed a cylindrical plastic tube 49 (namely, an extrusion which has been suitably cut to length) downwardly through passage 47 and into the base.

The cylindrical wall of base 19 is backed up by portion 46, and is therefore not expanded by the tube 49 despite the fact that the latter is preferably pressed into the base in a press-fit relationship. Thereafter, the portion 46 is elevated to a position above extrusion 49 and the mechanism 42 is operated to shift the base 19 and associated tube 49 to the next station as illustrated in FIG. 7.

At such next station, a backup portion 51 is inserted downwardly over tube 49 and over the cylindrical body of base 19. Connected to such portion 51 is an internal insertion element 52 which is shaped to force the locking and gas-sealing wad 18 downwardly into the base to thereby firmly lock the tube 49 to the base, this being a tight press-fit relationship which (again) does not expand the base due to the fact that the latter is backed up by element 51. A vent passage 53 is provided through insertion element 52 to permit escape of air as the element is inserted into the tube. Thereafter, elements 51 and 52 are lifted upwardly to positions above tube 49, and the base and tube are shifted to the next station as shown in FIG. 8.

Powder 21 is loaded into the tube 49 at such next station, FIG. 8, through a passage 54 in a loading portion 55 which is shifted downwardly over the tube 49 and the base. The quantity of powder is metered to provide the requisite gas pressure, etc.

At the next station, FIG. 9, the gas-metering wad 16 is first dropped down tube 49 so that it will be supported upon the powder 21 therein, following which an initial swaging and positioning means 56 is moved downwardly over the extrusion 49 and over the wad 16. The wads l6, 18, etc., are fed into the tube by suitable mechanism, not shown.

The swaging and positioning means 56 includes an outer or swaging portion having a tapered or frustoconical interior wall 57 adapted to cause tapering of substantially the full length of the tube 49. Such tapering is effected because of the pressure of the downwardly moving element 56, and also because such element 56 incorporates means to heat the wall 57 to a desired low temperature. In the illustrated embodiment, the heating means comprises an annular water chamber 58 through which water at a predetermined temperature is continuously fed via passages which are schematically represented at 59 and 60. Other heating means, for example electrical, may be employed in place of heated water.

It has been found that the temperature to which the wall 57 should be heated, the pressure of the downwardly moving element, the rate of swaging, and other factors, may vary somewhat in accordance with the wall thickness of the tube, the precise type of plastic of which the tube is formed, etc. Stated generally, the temperature of the swaging wall should be sufficiently high to make the plastic swageable at high pressures, but not sufficiently high to cause the plastic to shrink. The temperature also varies in accordance with the duration of the cycle, the temperature of the wall 57 being higher when the cycle is relatively short.

For the Plaskon 6- rigid polyethylene plastic, for example, the wall temperature may be surprisingly low and the cycle surprisingly short. Thus, for example, the element 56 may only be in contact with the tube for a fraction of a second, and the wall 57 need only to be heated to a temperature on the general order of about 100 F. The swaging pressure is high, being sufficient to create the indicated swage reduction.

The desired swaging occurs at such low temperatures that it is in the nature of cold working. The plastic is thus caused to have particularly desirable properties.

The positioning portion of element 56 comprises an interior element 59a which engages the upper end of metering wad 16 and causes the wad to be disposed at the proper elevation in the plastic tube. The element 59a, the tapered tube, and the powder 21 cooperate to maintain the metering wad 16 in the desired location. Element 59a has a suitable vent passage therethrough.

Referring next to FIG. 10, there is provided at the next station a swaging and positioning element 61 having a lower portion 62 which fits over the cartridge body and the base 19 for backup and positioning purposes. The upper portion of element 61 is suitably heated, for example by means of a water chamber 63 and associated passages 64 and 65. The portion of element 61 radially inwardly of water chamber 63 has a wall 66 shaped to initially neck-down the plastic in the vicinity of the tapered front portion of metering wad 16. In advance (upwardly) of the forward portion of metering wad 16, the wall 66 is adapted to commence effecting the elongated taper which forms the nose 12 of the cartridge body.

The powder-seal wad 17 (which is resilient in nature) is introduced into the cartridge body prior to downward movement of element 61, by suitable mechanism, not shown. It is positioned on the front or upper surface of wad 16 by an insertion element 67 having a vent passage 68 therethrough.

At the next station, FIG. 11, a swaging element 71 having a lower positioning portion 72 is moved downwardly over the plastic tube. A water chamber 73, through which water is fed via passages 74-75, is provided in element 71 in order to heat the plastic around element 16 and also around the nose. The interior wall of the element 71 inwardly of chamber 73 is shaped to neck-down the plastic at wad l6 and also to continue the tapering of the nose portion of the cartridge case. A suitable vent 76 is provided.

It is emphasized that the swage-reduction of the cartridge case adjacent and in advance of metering wad 16 not only continues the operation of forming the shoulder 14 and nose 12, but also effects a compression of powder-seal wad 17. A highly effective powder seal is thus achieved.

Referring to the next station, shown in FIG. 12, a swaging element 78 having a lower positioning and backup portion 79 is moved downwardly over the cartridge in order to effect further necking-down and tapering of the nose portion of the cartridge. As at previous stations, a water chamber 80 fed through passages 81-82 is provided, as is vent 83. The upper region of the element 78 is suitably shaped to commence starcrimping of the cartridge end, as indicated at 84.

At the next station, FIG. 13, a closure element 86 having a lower positioning and backup portion 87 is adapted to complete the evanescent crimp-closure 13. For this purpose, a water chamber 88 and associated passages 89-90 and vent 91 are provided.

After passing through all the stations, the shell is automatically fed out through a chute 92 (FIG. 4) into a packing mechanism. Although a completed cartridge is shown in the chute 92 at FIG. 4, it is to be understood that the cartridge would normally have passed down the chute 92 when the elements are in the illustrated positions. This is because FIG. 4 shows all of the parts after the associated forming elements have operated thereon, but prior to shifting to the next adjacent station.

Referring next to FIG. 14, there is shown schematically as associated with one of the elements, namely, number 86-87, a double-acting hydraulic cylinder apparatus 93 adapted to force the element 86 downwardly over the cartridge at a desired fluid pressure. A thermostatically controlled source 94 of water is shown as connected through hoses 9596 with passages 89-90, respectively. Although FIG. 14 shows only one of the stations, it is to be understood that similar hydraulic cylinders, and associated heating, charging or other apparatus, are provided at the other various stations as indicated above.

All of the elements 46, S1, 55, 56, 61, 71, 78 and 86 (FIG. 4) move up and down in substantial unison, but the pressure of each is individually controlled as is the temperature of the water passed therethrough (in those instances where water chambers are provided). Such conjoint movement is achieved by suitable valve means associated with cylinders such as the cylinder 93 of FIG. 14. The conjoint movement of the cylinders is correlated to the movement of the walking feed element 42, the latter operating when the swaging elements, etc., are in their uppermost positions and being stationary when the swaging elements are moved downwardly or upwardly.

Referring next to FIG. 15, it is an important feature of the present invention that the cartridge body is metal-coated as described hereinabove relative to FIGS. 3 and 3A. Metal-coating may be effected prior to the forming steps illustrated in FIG. '4, or may be effected after the cartridge has been otherwise completely manufactured. In the latter case, suitable means (such as paraffin) are provided to insure against ingress of fluid through the closure 13 or through the primer 20.

The coating may be effected relative to the elongated plastic extrusion from which the lengths of tubing 49 are cut. For example, the elongated extrusion is first fed through an oxidizing means adapted to effect oxidation of the exterior surface of the tube. Such oxidizing means may comprise a flame device, adapted to momentarily direct flame against the exterior surface of the tube, or it may comprise a suitable chemical. The oxidizing step conditions the plastic for reception of the inner or preparatory coating 36 (FIG. 3A). Such coating is very thin and is applied by means of the preplating bath I01 indicated schematically in FIG. 16. As an example, the preplating bath may comprise a lecherous nickel bath adapted to apply a coating only about 55 millionths of an inch thick, such coating being somewhat impregnated into the oxidized exterior surface of the tubing.

The precoating 36 prepares the tube for electroplating, which is effected in electroplating bath 102. For example, bath 102 may comprise an electrolytic nickel-plating bath adapted to apply the nickel coating (the exterior coating) which is represented at 35 in FIGS. 3 and 3A. As indicated hereinabove, coating 35 insures against jamming of the cartridge in the chamber despite extreme temperature conditions.

The plastic extrusion may also be coated after it is severed into the tubes 49, both the exterior and interior plastic surfaces then being metal-coated as shown in FIGS. 3 and 3A.

The foregoing detailed description is to be clearly understood as given by way of illustration and example only, the spirit and scope of this invention being limited solely by the appended claims.

Iclaim:

l. A method of making a blank cartridge, which comprises:

providing a generally tubular element formed of a thermoplastic synthetic resin which is capable of diameter reduction by swaging, swage-reducing one end portion of said tubular element to form an elongated hollow nose the diameter of which is substantially less than that of the remainder of said tubular element, and loading said tubular element with powder.

2. The invention as claimed in claim I, in which said method further comprises crimping the end of said nose to provide an evanescent closure adapted to open in response to firing of the blank cartridge.

3. The invention as claimed in claim 1, in which said swagereducing is effected by applying at a high pressure at least one die over said one end portion of said tubular element, said die having a relatively low temperature.

4. The invention as claimed in claim 3, in which said swagereducing is effected by applying at high pressures a series of progressively smaller low-temperature dies over said one end portion of said tubular element.

5. The invention as claimed in claim 4, in which each of said dies is applied for only a fraction of a second, and is heated to a temperature on the general order of about F.

6. The invention as claimed in claim I, in which said synthetic resin is a rigid linear polyethylene.

7. The invention as claimed in claim 1, in which said method further comprises providing a metal coating on said tubular element.

8. The invention as claimed in claim 7, in which said metal coating is applied by first oxidizing the surface of said tubular element, then applying a metallic undercoating to said oxidized surface, and then electrodepositing said metal coating on said undercoating.

9. The invention as claimed in claim 1, in which said method further comprises effecting said loading of said tubular element with powder prior to said swage-reducing step and by introducing said powder through said one end portion of said tubular element.

10. The invention as claimed in claim 1, in which said method further comprises inserting the other end portion of said tubular element into a generally cup-shaped base prior to said swage-reducing step and prior to said powder-loading step, and inserting a locking and gas-seal element into said other end portion prior to said swage-reducing step and prior to said powder-loading step, whereby said base is locked and sealed to said other end portion.

11. The invention as claimed in claim 1, in which said method further comprises providing a tapered wad formed of a solid and gas-impervious material, inserting said wad into said tubular element after said step of loading said tubular element with powder, and thereafter swage-reducing said tubular element into contact with said tapered wad whereby to form a tapered shoulder between said nose and the remainder of said tubular element.

12. The invention as claimed in claim 11, in which said method further comprises providing said tapered wad with a gas-metering passage the diameter of which is correlated to the gas-generating characteristics of said powder.

13. The invention as claimed in claim 1, in which said method further comprises providing a powder-seal wad in said tubular element, said powder-seal wad being adapted to disintegrate harmlessly in response to ignition of the powder charge contained within said blank cartridge.

14. The invention as claimed in claim 13, in which said method further comprises providing said powder-seal wad in said one end portion prior to said swage-reducing step and prior to said powder-loading step, and effecting lateral compression of said powder-seal wad in response to said swagereducing step.

15. The invention as claimed in claim 2, in which said method further comprises introducing the other end portion of said tubular element into a generally cup-shaped base, thereafter introducing into said other end portion a locking wad adapted to lock said other end portion to said base, thereafter effecting said step of introducing said powder into said tubular element through said one end portion thereof, and thereafter effecting at least the final stages of said swagereducing and crimping steps.

16. The invention as claimed in claim 1, in which said synthetic resin is a relatively rigid polyolefin.

17. The invention as claimed in claim 16, in which said polyolefin is a polyethylene characterized by a high degree of linearity and crystallinity and having a high molecular weight.

18. The invention as claimed in claim 1, in which said synthetic resin is selected from a group consisting of linear polyethylenes, polypropylenes of high isotacticity, styrene butadiene acrilonitrile terpolymer, ethyl cellulose, and cellulose acetate.

19. The invention as claimed in claim I, in which said tubular element is an extrusion which is open at both ends, in which said method further comprises closing said other end of said extrusion prior to said step of loading said extrusion with powder, and effecting said powder-loading step through said one end portion and prior to at least the final portions of said step of swage-reducing said one end portion.

Claims

1. A method of making a blank cartridge, which comprises: providing a generally tubular element formed of a thermoplastic synthetic resin which is capable of diameter reduction by swaging, swage-reducing one end portion of said tubular element to form an elongated hollow nose the diameter of which is substantially less than that of the remainder of said tubular element, and loading said tubular element with powder.

2. The invention as claimed in claim 1, in which said method further comprises crimping the end of said nose to provide an evanescent closure adapted to open in response to firing of the blank cartridge.

3. The invention as claimed in claim 1, in which said swage-reducing is effected by applying at a high pressure at least one die over said one end portion of said tubular element, said die having a relatively low temperature.

4. The invention as claimed in claim 3, in which said swage-reducing is effected by applying at high pressures a series of progressively smaller low-temperature dies over said one end portion of said tubular element.

5. The invention as claimed in claim 4, in which each of said dies is applied for only a fraction of a second, and is heated to a temperature on the general order of about 100* F.

6. The invention as claimed in claim 1, in which said synthetic resin is a rigid linear polyethylene.

14. The invention as claimed in claim 13, in which said method further comprises providing said powder-seal wad in said one end portion prior to said swage-reducing step and prior to said powder-loading step, and effecting lateral compression of said powder-seal wad in response to said swage-reducing step.

15. The invention as claimed in claim 2, in which said method further comprises introducing the other end portion of said tubular element into a generally cup-shaped base, thereafter introducing into said other end portion a locking wad adapted to lock said other end portion to said base, thereafter effecting said step of introducing said powder into said tubular element through said one end portion thereof, and thereafter effecting at least the final stages of said swage-reducing and crimping steps.

19. The invention as claimed in claim 1, in which said tubular element is an extrusion which is open at both ends, in which said method further comprises closing said other end of said extrusion prior to said step of loading said extrusion with powder, and effecting said powder-loading step through said one end portion and prior to at least the final portions of said step of swage-reducing said one end portion.