US2919647A

US2919647A - Ammunition

Info

Publication number: US2919647A
Application number: US357391A
Authority: US
Inventors: John C Dear; Robert G Owens; Ronald A Gulley
Original assignee: Olin Corp
Current assignee: Olin Corp
Priority date: 1953-05-25
Filing date: 1953-05-25
Publication date: 1960-01-05
Anticipated expiration: 1977-01-05
Also published as: GB757645A; BE591714Q

Description

Jan. 5, 1960 .1. DEAR mm 2 9 AMMUNITION Filed May 25. 1953 COATING: 8 ON I ICD. l

INVENTORS JOHN C. DEAR BY ROBERT e. owzws RONALD A. GULLEY ATTORNEYS;

AMlVIUNITION John C. Dear, East Alton, and Robert G. Owens, Wood River, 111., and Ronald A. Gulley, Jenn ngs, Mo., assignors to Olin Mathieson Chemical (Jot-partition, a corporation of Virginia Application May 25, 1953, Serial No. 357,391

9 Claims. ((11. 102-'42) This invention relates generally to ammunition and more particularly to a novel shot shell having improved ballistic characteristics.

At one time, shot shell cases were extensively made of brass but, in order to compensate for the cost thereof, most consumers were forced to reload the case as many times as the case would permit. As a result, as soon as a procedure was developed for making an expendable shot shell case from a paper tube and a brass head, manufacture of the brass shell case was almost entirely discontinued in favor of the newer development. The paper shot shell case has been found eminently suitable for most purposes but it has been found that it does not always function properly after exposure to humid weather conditions or when it is fired at temperatures of 32 F. or lower. Because of these dificiencies of the paper shell, there has been a constant endeavor to develop an expendable shot shell case which is not deleteriously affected by inclement Weather but none of the substitutes heretofore proposed, including steel shot shell cases, have been sufiiciently advantageous to replace the paper shot shell in practice. Although aluminum rifle cartridge cases have been proposed in the art, attempts to make shot shells having an aluminum case have been unsuccessful for various reasons. One of the most disconcerting problems encountered in making a suitable aluminum shot shell has been to obtain satisfactory ballistic characteristics. Heretofore, shot shells having an aluminum case and loaded with a powdersuitable for imparting the proper velocity to the shot have almost without an exception produced dangerously high pressures when the shell was fired.

It is therefore an object of this invention to provide a novel and expendable shot shell case. It is another object of this invention to provide a shot shell having an expendable case which will function properly in a shotgun in inclement weather. Another object of the invention is to provide a shot shell having an aluminum case and having satisfactory ballistic properties. More speecifically, it is an object of this invention to provide a shot shell having an aluminum case which can be loaded to have ballistic properties equivalent to the paper shot shell under all weather conditions and which will also function satisfactorily in a shotgun under inclement weather conditions. Another object is to provide a method for improving the ballistic performance of aluminum shot shells.

The foregoing objects as well as others are achieved in accordance with this invention by providing a shot shell having an aluminum case separated from the metallic shot contained therein by a layer of a non-metallic material. lt has been found that a shot shell having an aluminum case containing a powder suitable for paper shells can be loaded to the required shot velocity without hazardous pressures being developed when the shell is fired provided contact between the inner wall of the shell case and the metallic shot is prevented by an intervening layer of a non-metallic material.

Additional objects and advantages will be apparent from the following description and drawings in which:

Figure 1 is a schematic partial sectional view ,of an embodiment of the invention showing a shot shell with a coating applied to the inner wall of the shell case;

Figure 2 is a schematic partial sectional view of another embodiment of the invention showing an aluminum shot shell with a coating applied to the shot pellets.

Referring to the drawings this invention contemplates a shot shell provided with an aluminum shell case 1 having a hollow 2 defined by said walls 3. The hollow 2 contains shot pellets 4, and an over powder wad 5 separating the shot pellets 4 from a powder charge 6. The shot pellets 4 are held in the hollow 2 by a top wad 7. Any suitable primer may be provided for igniting the powder 6. The aluminum shot shell is provided with a substantially continuous and adherent non-metallic coating 8 on the surface of either the shot 4, as illustrated in Figure 2, or the inner wall 3 of the shot shell case 1, as illustrated in Figure 1, or both. Any non-metallic material which can be applied to either the shot 4 or the inner wall 3 of the shell case l in the form of a substantially continuous film 8 and which will not otherwise interfere with the performance of the shot shell can be utilized. For example, non-metallic films of natural occurring resins such as ester gum and the like, films of synthetic resins such as ethyl cellulose, phenol formaldehyde, polystyrene, polyesters, epoxy and the like, films of a lacquer such as a nitrocellulose lacquer and films of a wax such as paraffin wax, microcrystalline wax, carnauba wax, ceresin wax and the like have been found admirably suited for the purpose. The resins and waxes can usually best be applied in the form of a solution thereof by dipping, spraying, or other conventional coating process. For best results the melting points of the coating should be above about 120 F. In a preferred form of the invention illustrated in Figure 1 the shot and inner wall of the case are separated by a layer of aluminum oxide adhering to the inner wall of the case. Coatings of other aluminum compounds such as aluminum fluoride, for example, are also suitable for the purpose. Only that portion of the inner wall 3 of the aluminum shot shell case 1 adjacent the shot 4 charge need be coated but no special precautions need be taken to prevent the entire inner wall from becoming coated. The thickness of coating 8 required is not necessarily critical although it must be substantially continuous and it must be of such thickness and strength that it can withstand any abrasion thereof caused by the various other components of a shot shell as they are inserted therein during loading. The aluminum oxide coating on the inner wall 3 of the case 1 can be applied by conventional chemical methods but is preferably applied by an anodic treatment and must exceed the thickness of the oxide coating produced by oxidation of aluminum in the air. Best results have been obtained with an anodically produced oxide coating of from about 10 microns to about 20 microns thickness on the inner wall of the case. Likewise, the thickness of the other non-metallic adherent films on the inner wall of the shot shell case or on the shot should preferably be Within this range.

In older to clarify and to more fully describe the invention the following is a description of embodiments thereof:

Conventional lead shot 4 is placed in an oblique tumbling barrel such as is conventionally used for cleaning shot and a solution of about 10 parts Socony Vacuum #2300 microcrystalline Wax marketed-by the Socony Vacuum Oil Co. of New York and about parts can brass shell case.

2,919,647 r. g r

bon tetrachloride is sprayed on the shot. The solution is applied to the shot by spraying a small amount thereon and then tumbling the shot a while to permit the solvent to evaporate after which more solution is added, the intermittent spraying and tumbling process being continued until a wax film of about to 20 microns thickness substantially completely covers the shot. After solvent removal by tumbling to facilitate evaporation thereof, the shot is ready to load in the aluminum shot shells.

In another embodiment of this invention, an aluminum shot shell case 1 is immersed about 30 seconds in a solution of from about four to about five ounces sodium hydroxide per gallon of water maintained at a temperature of about 180 F. After rinsing in water to substantially completely remove any sodium hydroxide solution clinging thereto, the shell case is anodized about 30 minutes in a percent sulfuric acid-water solution at a current density of 12 to 15 amperes per square foot. The temperature of the solution during the anodizing treatment is maintained within the range of about 68 F. to about 74 F. Conventional anodizing equipment is used, although an anode is placed within the cartridge case to insure the formation of a coating of at least about .001 inch thick on the inner wall 3 of the case 1. After rinsing in water to remove the sulfuric acid solution, the shell case is immersed about 30 minutes in a solution of about one-half ounce nickel acetate per gallon of water at a temperature of about 200 F. The shell case is then rinsed'to remove the nickel acetate solution therefrom and is air dried.

No definite explanation of why the problem solved by this invention was encountered in the manufacture of shot shells and not in rifle cartridges or why a nonmetallic coating interposed between the shot 4 and the wall 3 of the shot shell case 1 of a loaded shot shell improves the performance thereof is apparent at this time. metallic barrier prevents seizure between the shot and the inner Wall of the shot shell case. 'In a shot shell, the shot charge 4 consisting of many small spherical pellets can be considered to be essentially a fluid body exerting pressure in all directions when the shell is fired. Thus, there is a tendency for the shot 4 to move radially against the shell wall 3 and consequently, movement of the shot out of the shell case is retarded. It is believed the pressures exerted by the shot 4- radially against the shell case wall 3 increases the resistance of the shot charge against forward motion and that this resistance is responsible for the high pressures obtained when an aluminum shot shell not having the barrier provided by this invention is fired. The non-metallic coating is believed to reduce the friction between the shot and the shell case wall making it possible to propel the shot at the desired velocity with the development of less pressure. In a rifle cartridge, the projectile is a single body and does not exert a great radial pressure against the cartridge case. Tests have consistently shown a distinct improvement'in shot shells of all gauges provided by this invention over shot shells having an aluminum case not separated from the shot by a nonmetallic coating. As an example, 410 gauge shells made in accordance with this invention and loaded to have a velocity of about 1000 feet per second at a distance of about 25 yards from the muzzle of the gun using a conventional shot shell powder 6, developed a pressure of from about 2000 to 3000 pounds per square inch less than did similar but untreated aluminum shot shells.

The aluminum shot shell provided by this invention will function properly in inclement weather and it has been found that the case can be manufactured at a cost which will not require the consumer to reload the case. Although the price per pound of aluminum at the-present time is substantially equal to that of brass, the "finished shot shell case costs only about one-third the cost of a This lower cost is primarily due tothe lighter weight 'of the aluminum but is also partially due It has been theorized, however, that the nonto the fact that aluminum shot shell cases can be more easily formed by extrusion processes than can shell cases be formed from brass. Furthermore, the shot patterns obtained with the aluminum shot shell provided by this invention are substantially equal to those of the paper shot shells because neither the non-metallic coating on the shot or the case interferes with the proper shot dispersion during the flight of the shot.

While this invention has been described in detail in the foregoing, variations or modifications within the skill of the art can be made therein without departing from the spirit and scope of the invention. The 410 gauge shot shell has been used herein as an example but the invention is applicable to other gauges including 12, 16 and 20 gauge shot shells. i

Having thus described the invention what is claimed and is desired to secure by Letters Patent is:

1. A shot shell comprising an aluminum case having a hollow defined by an inner surface of said case and containing a powder charge and a plurality of metallic shot pellets each having an exterior surface and exerting a radial pressure against the surface of the hollow during firing, and means to reduce the pressure developed by the powder charge during firing, said means comprising a non-metallic coating on one of said surfaces and separa'ting said aluminum case and said shot pellets.

2. A shot shell comprising an aluminum case having a hollow defined by an inner surface of said case and containing a powder charge and a plurality of metallic shot pellets each having an exterior surface and exerting a radial pressure against the surface of the hollow during firing, and means to reduce the pressure developed by the powder charge during firing, said means comprising a non-metallic coating greater than about 10 microns thickness on one of said surfaces and separating said aluminum case and said shot pellets thereby preventing seizure between the metallic shot pellets and the aluminum shot she'll case.

3. A shot shell comprising an aluminum case having a hollow defined by an inner wall in said case and containing a powder charge and a plurality of metallic shot pellets exerting a radial pressure against the wall of the hollow during firing, and means to reduce the pressure developed by said powder charge during firing, said means comprising a non-metallic coating greater than about 10 microns thickness on said wall of the hollow of said aluminum case and separating said wall and said shot pellets thereby preventing seizure between the metallic shot pellets and the aluminum shot shell case.

4. A shot shell comprising an aluminum case having a hollow defined by an inner wall in said-case and containing a powder charge and a plurality of metallic shot pellets exerting a radial pressure against the wall of the hollow during firing, and means to reduce the pressure developed by the powder charge during firing, said means comprising a non-metallic coating greater than about 10 microns thickness on said metallic shot pellets thereby separating said wall of thehollow in said aluminum case and said shot pellets and preventing seizure between the metallic shot pellets and the aluminum shot shell case.

5. ,A shot shell having an aluminum case and metallic shot pellets and displaying substantially the same characteristics as a conventional paper shot shell of the same gauge and load of shot pellets when provided with the same powder charge as in said paper shot shell, said shot she'll comprising an aluminum case having a hollow delined by an inner surface of said case, a plurality of metallic shot pellets within the hollow exerting aradial pressure against said inner surface during firing, each of said shot pellets having an exterior surface, means to adjust the pressure developed by the powder charge-and the velocity of the shot pellets to that commensurate with said paper shot shell, said means comprising a non-metallic coating greater than about 10 microns thickness on one of said surfaces and separating said aluminum .case

and said shot pellets thereby preventing seizure between the metallic shot pellets and the aluminum shot shell case.

is an aluminum oxide on said aluminum case.

References Cited in the file of this patent UNITED STATES PATENTS Spengler Feb. 6, 1940 FOREIGN PATENTS Great Britain of 1894 Great Britain Oct. 27, 1936 Great Britain May 26, 1937 Great Britain Oct. 23, 1940

Claims

1. A SHOT SHELL COMPRISING AN ALUMINUM CASE HAVING A HOLLOW DEFINED BY AN INNER SURFACE OF SAID CASE AND CONTAINING A POWDER CHARGE AND A PLURALITY OF METALLIC SHOT PELLETS EACH HAVING AN EXTERIOR SURFACE AND EXERTING A RADIAL PRESSURE AGAINST THE SURFACE OF THE HOLLOW DURING FIRING, AND MEANS TO REDUCE THE PRESSURE DEVELOPED BY THE POWDER CHARGE DURING FIRING, SAID MEANS COMPRISING A NON-METALLIC COATING ON ONE OF SAID SURFACES AND SEPARATING SAID ALUMINUM CASE AND SAID SHOT PELLETS.