Cartridge

[57] ABSTRACT

A blank or propellant gas cartridge having a casing of generally tubular form with a telescopically reverse in-folded star-crimp closed integral tubular end section, and within which is contained a blank propellent powder charge, with a readily rupturable low tensile strength discrete particulate mass adhesively self-bonded in a total initial restraining mass form between the propellent powder charge and the in-folded telescoping star-crimp closed end of the casing.

Claims, 2 Drawing Figures

<img file="US3672301A_D0001.tif" />

PATENTED JUH 27 1972

3,672,301

<img file="US3672301A_D0002.tif" />

<img file="US3672301A_D0003.tif" />

FIG. 2

<img file="US3672301A_D0004.tif" />

3,672,301

CARTRIDGE

This invention relates to a cartridge of the type which might normally be designated as a blank cartridge or as a propellent gas cartridge.

It has been conventional practice in the art of blank cartridges or propellent gas cartridges to provide shotgunadapted cartridges which might be employed in standard shotguns. In providing such blank cartridges it is desirable that a propellent charge be employed which is of the smokeless type, as a full propellent charge of black powder has many disadvantages, including the formation of substantial smoke, highly corrosive gases, and solid residues. Such smokeless powder normally requires the containment thereof under a pressure substantially in excess of atmospheric pressure, e.g. several hundred psi or more, in order to maintain and complete burning after initial ignition. In prior blank cartridges the desired propellent pressure has been maintained by restraining the propellent within the shotgun shell through the medium of a large quantity of cardboard discs, commonly known as wads, in front of the propellent charge. Such cardboard wads achieve the desired restraining and propellent self-pressurizing function, but result in a substantial disadvantage in that the expulsion of the wads from the gun bore is often essentially as an intact wad mass at high velocity, and of effectively substantial unit inertial mass, thereby providing a hazardous high velocity projectile of sufficient inertial mass to inflict serious injury on a person. In addition, such large mass and size projectiles are undesirable when the blank cartridge is used in some important gas propellent use devices, such as in projectile launchers which embody lateral gas port chambers, as in U.S. Pat. No. 3,318,033, as the relatively large size cardboard wads, which are also relatively tough and difficult to break up into pieces, tend to clog the relatively smaller lateral gas ports very rapidly and may well result in dangerous malfunction of the firing weapon. In a further prior blank cartridge, an attempt has been made to overcome the cardboard wad projectile problem by forming the cartridge case of a closed cylindrical brass body which, due to its rupture strength, contains the propellent and propellent gases during burning up to a given rupture pressure, and thereafter ruptures to release the propellent gases. This latter metal cartridge case blank cartridge has the substantial disadvantage of causing the formation of sharp edges along the zone of rupture of the cartridge body after bursting at the integral closed forward end, and in addition is relatively high in cost of manufacture, particularly relative to the cost of manufacture of the cardboard wad construction which employs standard shotgun cardboard shell casings.

It is an object and feature of the present invention to provide a relatively inexpensive cartridge of the blank or gas propulsion type, and which may be employed in gas propulsion launching arrangements which have restricted gas ports therein, such as U.S. Pat. No. 3,318,033.

Still another object and feature of the invention is the provision of a cartridge which enables the employment of smokeless propellent powder without the necessity for either a metal retaining casing body or the conventional multiple cardboard discs, and which employs a restraining construction which is itself effective in pressure retention while enabling a high degree of frangible comminution of the expelled portion thereof during and after expulsion from the cartridge casing.

A further feature of the invention is to provide a blank cartridge which is relatively safe in usage, in that a constraining construction is employed which enables a desired degree of self-pressurizing constraint on the burning propellent charge, a part of which constraint is afforded by the overall construction of the casing and a portion thereof by the combination employment therewith of a frangible restraining wad disc which is formed of discrete particles of low inertial mass bonded together, and offering low overall mass tensile strength, to form an effective single wad which is itself effectively readily broken into a large quantity of relatively small particles of low mass upon and as a concomitant part of the expulsion thereof from the cartridge case, to thereby provide minimal projectile danger upon expulsion from the gun barrel and also minimal gas port clogging effect. ’

Still other objects, features and attendant advantages will become apparent to those skilled in the art from a reading of the following detailed description of a preferred embodiment constructed according to the invention, taken in conjunction with the accompanying drawing wherein:

^FIG-1 is ^a perspective view, partially broken away, of a car^υ tndge according to the invention.

FIG. 2 is a longitudinal section view of the cartridge of FIG.

Referring now in detail to the figures of the drawing, in a 15 preferred embodiment a cartridge 11 is formed, including a case 13 which may be formed with a base cup 17 of metal such as brass, a body tube 15 frictionally joined to and within the base cup 17 as by crimping of the base cup 17 about the body tube 15, and a stationary base plug 21 contained within the ₂₀ body tube 15. The base plug 21 may be formed of a single molded mass of thermosetting or thermoplastic plastic such as polyethylene, hard rubber, or the like, or may be a composite laminated mass, as may be desired. Body tube 15 is preferably crimped about the base cup end of the base plug 21 25 as indicated at 15α, and in order to inexpensively and effectively seal the junction between the base plug 21 and the case 13 the base plug is formed with an annular obturating flange 21α facing the propellent charge chamber of the cartridge. Alternatively, base plug 21 and body tube 15 and/or base cup 17 may be formed as a single integral molded mass of suitable material such as polyethylene or polypropylene.

Base plug 21 has an axial bore formed therethrough, into which may extend an internal base cup nipple 17α, and within which is press fit a primer 19, which may suitably be a stan35 dard percussion primer. The forward end of the bore 21α in base plug 21 is filled with a suitable ignition charge 23, which may suitably be conventional black powder, and which serves to ignite the main propellent charge 25 which is disposed within a cavity or chamber formed between the forward obtu40 rating face of base plug 21 and the rear facing face of a frangible restraining wad 27 of special construction. The main propellent charge may be and is preferably a standard blank powder charge, of the type which requires a constraining pressure substantially above atmospheric pressure, as of the order of se veral hundred psi or more, for sustained burning after initial ignition by the ignition charge 23, and which type of propellent charge is generally termed as smokeless. Various charges 25 are available for this purpose, dependent upon ₅₀ whether the charge is to be used for gas propellent purposes or merely as a blank for audio simulation purposes, or some combination or other use thereof. In the instance of utilization of the invention for propellent purposes primarily, I have found that a main propellent charge 25 of standard blank powder, 55 conventionally identified as WC Blank and manufactured by

Olin Mathieson Chemical Corporation, is satisfactory, employing 18.5 grains thereof, with an ignition charge of 1.5 grains of fine black powder.

The constraining wad 27 in the preferred embodiment is of 60 ^{a s}P^ecial construction, being a composite disc wad formed of discrete small particles of cork bounded together in a generally cylindrical mass by a suitable relatively low bond adhesive, such as paraffin, the wad disc preferably having relatively low strength thin paper sheet coverings at its forward 65 and rearward ends, as indicated at 27α and 27b respectively, for purposes of initial ease of handling and cartridge assembly without breaking or rupturing. A commercially available material which I have found to be suitable for forming the low tensile low mass soft particulate wad disc 27, is Sacork, which 70 I have found usable in thicknesses of from approximately three-eighths to one-half inch in 12 gauge cartridge constructions.

The cork wad disc 27 has an outside diameter which is complementary to the internal diameter of case body tube 15, and ⁷⁵ is retained in its initial position as shown in FIGS. 1 and 2,

3,672,301 through the medium of a special cooperating constraining construction of the case 13 which enables the otherwise relatively low tensile strength wad to effectively constrain the burning propellent charge sufficiently to enable a desired degree of burning of the charge, while also enabling the low 5 strength wad disc 27 to be subsequently broken apart and expelled from the cartridge in a highly comminuted low mass relatively soft particulate form.

This special cooperating construction of the case 13 for initial constraining reinforcement of the particulate cork wad 10 disc 27 is provided by forming the case 13 with an integral reverse in-folded or in-rolled tube extension 13Z&gt; which connects with the main external longitudinal portion of the case 13 through an annular reverse roll 13α, and this reverse tube extension 13Z&gt; is extended into end engagement with and 15 closed across the forward face 27α of the cork wad disc 27. A desired structural strength and ease of forming is preferably achieved by forming the lateral closure across the forward face 27α of the cork wad disc by a generally radial or star crimp configuration 13c, which is preferably bounded at its 20 center section as by a thermoseal or adhesive bonding thereof, as indicated at 13r, and if desired a further seal may be effected for water proofing purposes by a drop of wax 13r, such as paraffin. To this end, the body tube 15 of case 13 is preferably formed of a suitable thermoplastic material, such as 25 extruded polyethylene or polypropylene, which enables ease of formation(and desired reverse unrolling in fired operation) of the forward reverse roll and tube extension 136, with star crimp closure 13c and thermoseal 13s, as illustrated in the preferred embodiment. 30

In operation, the cartridge 11 is inserted in the standard manner in a conventional shotgun, although it will be apparent that the cartridge may be made of a suitable size for use in other weapons, as may be desired. Upon insertion into the weapon cartridge chamber, the cartridge 11 is fired by percus- 35 sion striking of the primer 19 as by a firing pin in the conventional manner, and ignition charge 23 will thereupon be ignited and will correspondingly ignite the main propellent charge 25. The propellent charge 25 will thereupon generate a gas product which will exert a forward motion pressure on the 40 particulate cork wad disc 27. This forward motion pressure will be effectively resisted by the cork wad disc 27 through the axial substantially full forward surface back-up provided by the reverse roll tube extension 13b and star-crimp lateral closure 13c thereof. The pressure of the main propellent charge 45 25 will continue to be raised while the propellent charge continues to burn, and the cork wad disc 27 will be accelerated forward as a result of the pressure increase and the overcoming of the resistence offered to forward motion by the infolded reverse tube extension 13b. This forward motion of the 50 cork wad disc 27 will be accompanied by unrolling of the reverse tube extension 13b to its forward unrolled position where it will form an effective longitudinal extension of the illustrated outer tubular portion of the case 13, and thereupon the pressure within the thus expanded chamber containing the 55 burning propellent charge 25 will effect rupture of the starcrimp closure 13c, 13s, thereby outfolding and spreading the star crimp closure into its natural tubular configuration and which will thereby form a further extension of the case 13 beyond that formed by the reverse tube extension 136. The 60 cork wad disc 27 will in the process of passing through this spreading star-crimp closure be broken up into a large number of small discrete particles or groups of particles of cork which are of very low mass. These small size comminuted cork particle fragments pose substantially little problem in discharge 65 through relatively restricted lateral restriction orifices, as are encountered in the construction of U.S. Pat. No. 3,318,033, and are even further broken up upon exit from the weapon muzzle and entry into the open atmosphere. The breaking of the restraining wad 27 into these comminuted low mass soft 70 particle fragments also has the distinct advantage of presenting relatively low danger to operating personnel in front of the ^bIast’ personnel are disposed beyond a zone of 10 or 12 feet from tne weapon muzzle. The particulate cork wad disc 27 additionally serves the important advantage of insulating the propellent 25 from the star-crimp closure end 13c during the preferred heat sealing closure of the star-crimp, as indicated at 13r.

While the invention has been illustrated and described with respect to a single preferred embodiment, it will be apparent to those skilled in the art that various modifications and improvements may be made without departing from the scope and spirit of the invention. Accordingly, the invention is not to be limited to the specific illustrative embodiment, but only by the scope of the appended claims.