US1892759A - Ammunition - Google Patents

Description

Jan. 3, 1933.

W. H. WOODFORD AMMUNITION Filed March 19, 1930 i ATTORNEYS.

for using such a lubricant as material 0 with the steel surface exposed .By after-corrosion is meant the as y . residues from some types of ammunition WATSON H. WOODFOBD, OF BRIDGEPORT, CONNECTICUT, ASSIGNOR T0 REMINGTON S COMPANY, INC., A CORPORATION OF DELAWARE istr'UNITION Application filed March 19, 1980. Serial No. 486,988.

5 wall of the gun bore a coating or film which will effectively protect-the bore against corrosion even under the most adverse conditions of humidity and temperature.

It is a further object of the present inven- 11: tion to provide a projectile coated with a material which presents a dry surface and is at the same time highlyefiective as a lubricant for the projectile during its passage through the bore of the gun. The necessity grease, which possesses many disadvantages, is thereby dispensed with. I

It is a further object'of the present invention to provide a projectile coated with a resenting a highly lustrous and attractive nish, and which, in addition, is not susceptible to rapid oxidation or corrosion, and which thereforegives good protection against deterioration of the projectile itself. The evil known as after-corrosion in gun barrels has for a long time been a troublesurface onex posure to the atmosphere will rust, and this is likewise true in connection in the bores of. guns. 7

corrosion which occurs in the bores of guns after shooting, the activity of which corrosion. has been greatly augmented heretofore the deposit, inthe bores of the guns, of

when fired in the guns; 7 This has been especially true in the past where ammunition priming mixtures were used containing such 40 an ingredient as potassium chlorate, which leaves hygroscopic residuesjin the gun bore, which residues become lodged in the fissures and tool wounds of the bore surface, and which attractmoisture from the atmosphere,

in the presence of which aravaging corrosion of the steel of'the bor'etakes place.

Efforts to overcome after-corrosion have for the most part been directed toward the discovery of ingredients for the explosive constituents of ammunition which would not w some problem. I As is well known, any steel only satisfy the rigid ballistic and stability requirements, but would, in addition, leave no residues of a hygroscopic nature, and which would therefore assist in preventing after-corrosion in gun bores. Such ammunition has been successfully produced and used, but it is to be noted that this ammunition does not in a positive manner prevent corrosion in the gun bore, inasmuch as it does not leave a protective coating in the bore of the gun, but merely is not capable of leaving objectionable residues of a nature which might promote corrosion. v I

Further methods of combatin the evil of after-corrosion have involved t e provision of certain ingredients in the explosiveconstituents of ammunition which appear to react with the material forming the bullet surface to actually form a corrosion preventive film in the bore of the gun in which the ammunition is fired. Such ammunition has been produced and used with success, but in thls ammunition the available ran e in the choice of explosiveingredients, w ich will successfully attain theseresults is quite limited. Itis obviously highly desirable that ammunition be produced which is capable of preventmg corrosion in the gun bore without the necessity thereby' 'oflimiting the range in the choice and selection of successfully operative ingredientsfor the explosiveconstituents of this ammunition. Furthermore, in thisfammunition the bore coating characteristics appear to be dependent upon the joint' use of particular explosiveingredients,'together with a bullet liavinga surface of a particular material. In connection with this am munition tests haveindicated that success in forming a protective coating in the gun bore is apparently due to some form of reaction between the explosive'ingredients'and bullet material. It is desirable that corrosion pre-' ventive ammunition be produced in. which any of the common types of projectiles, already in use, may be utilized, and in which the successful formation of a bore'protective coating-may beefiected without dependence upon'any form of reaction between the ingredients of the ammunitionand the material of the projectile. The presentinvention aims In metal fouling, fragments of metal are torn from the bullet and deposited as isolated patches in the gun bore, and as repeated 'firmgs take place this fouling accumulates,

resulting in impaired acuracy, reduction of bore diameter, as well as rendering the gun unsafe. Grease has been much used as a lubricant on bullets to prevent metal fouling, but the use of grease is attended by many serious disadvantages, such as the difliculty of retaining the grease on the projectile and the undesirable accumulation of foreign matter by the grease. Various so-called dry lubricants have been proposed, most of which constitute a soft metal applied as a jacket or deposit on the projectile. The present invention contemplates the provision of a projectile coated with a metal which not only functions to prevent bore corrosion but also constitutes a dry lubricant of superior bullet lubricating qualities and which very effectively acts to prevent metal fouling.

' According to the present inventionthehereinbefore mentioned and still further objects are fulfilled, as will be apparent from the following specification, by the application of the metalcadmium to projectiles, preferably in the form of coatings applied to the surfaces of the projectiles.

The natural corrosion preventive properties of cadmium are well known. A cadmium coating on a steel surface is known to be high- 1y efficient in protecting the steel against rust, this coating being superior in many respects to coatings of other metals which have been long used for rust prevention, such for example as zinc and tin. The element cadmium stands near the element iron in the electromotive series and will not deteriorate as rapidly from anodic attack as other metals more remote from iron in the series. At the same time, cadmium is electro-positive with respect to iron and will protect iron in accordance with well established electro-chemical principles. The utilization of these and other well known desirable properties of cadmium is contemplated in connection with the pres ent invention. In addition, the discovery of heretofore unknown properties of cadmium is involved as an important phase of the invention.

It has been discovered in connection with experiments leading to the present invention that new and highly advantageous results are obtained when projectiles coated with cadmium are fired in guns. A gun barrel having such projectiles fired therein is found to be left with a highly lustrous coating. on the walls of the bore. The coating'or film thus formed is very thin and is uniformly distributed throughout the bore. Thisfilm fills the microscoplc fissures and tool wounds in the steel of the bore and prevents accumulation of hygroscopic residues which would attract and hold moisture and thereby promote corrosion. At the same time thefilm serves to act as a bar against contact of the steel with the atmosphere and thus, in 'a positive manner, actually prevents corrosion of the bore surface. In addition, considering the electrochemical properties heretofore mentioned, the higher electrode potential of cadmium in the electromotive series causes the cadmium to guard the bore steel against galvanic attack, and at the same time the proximity of cadmium in the series assures the cadmium against rapid deterioration by anodic attack. Tests have demonstrated that gunbarrels, after having a few cadmium plated bullets shot therein, are capable of withstanding exposure to severe atmospheric conditions without a sign of corrosion in the bore. In one instance, several cartridges having cadmium plated bullets were fired in a barrel, and this barrel was then placed in a chamber of heated and highly humidified air. After confinement of this barrel to this chamber for a period of over two weeks, examination showed the bore to be bright and entirely free from rust, While parts of the barrel, other than the bore, were found to be heavily rusted. This test was carried on in its entirety without in any way cleaning or treating the bore of the barrel, other than applying cadmium as above described. Repeated firing of cadmium plated bullets in a gun has shown that the protective coating or film in the bore remains thin and uniformly distributed, and that the diameter of the bore is not materially altered even after a large number of bullets have passed through the bore.

The projectilemay be provided at its surface with cadmium by any suitable means. The projectile may be dipped into a molten bath of cadmium, if desired. Or, the molten cadmium may be applied to the projectile as by spraying; or the coating may be formed by electrical deposition, or by any other suita l e depositing method. Further, the coating may be applied as a previously formed jacket, plate or band, 'etc., if desired. In-

asmuch as electrical deposition affords a means whereby the thickness of the coating may be easily controlled, and as only a very thin coating of cadmium is required to perform the desired results successfull I prefer to coat the projectiles by this met od. The well-known electrical barrel plating process, utilizing a cadmium cyanide solution.

constitutes a very suitable plating method for accomplishing the purposes of the present invention. J p

The entire surface of the projectile may be cadmium plated, thereby causing the projectile to present an attractive surface over its entire area. After plating with cadmium, the surface may be polished or finished in any suitable manner, thus providing a bright surface which is found to be capable of holding its lustre over a long period of time. It will be understood, however, that it is not essential to coat the entire surface of the projectile with cadmium, but that the above described bore coating effects may be obtained by providing cadmium on only such portions of the projectile which engage the rifling of the gun or which contact the bore surface. In projectiles 'of the type having rifling bands formed thereon the cadmium may beconfined to the rifling band only, if desired. I prefer, however, to coat the entire projectile in order to obtain the attractive finish as Well as the protection to the projectile itself, which cadmium affords.

It will be understood also, as mentioned above, that the cadmium may be applied to the projectile as a previously formed jacket, if desired, after methods known in the art in connection with jackets of other materials. However, due to the fact that but a very thin coating of cadmium is required, and for the sake of economy, it is preferred to apply the cadmium to the projectile by some form of depositing process.

In the drawing, which forms a part of this specification, there are illustrated on an enlarged scale several representative types of projectiles embodying the present invention.

In Fig. 1 is shown in elevation, partly in section, one type of projectile embodying the invention.

In Fig. 2 is shown a similar view of another type of projectile embodying the present invention.

In Fig. 3 is shown a similar view of still another type of projectile embodying the present invention.

The projectile of Fig. 1 is a standard lead bullet of the type popularly used with small calibre ammunition, such as for the .22 calibre rifle. The bullet proper, indicated at 10, is formed of lead, and a rifle band 11, is formed on its outer surface integral with the body of the bullet. The entire surface of the bullet is provided with a thin coating or plating 12 of cadmium, which besides serving in the capacity of forming a protective coating in the gun bore, serves also as a protcctive coating of attractive appearance for the bullet itseL The projectile illustrated in Fig. 2 is a rifle bullet of the mushrooming type. A jacket 13, of copper, gilding metal, or other metal or alloy, is filled with a core 14 of lead or material having high percentage of lead. The nose of this projectile is provided with an aperture 15, and the jacket to the rear of this aperture is weakened as at 16 to facilitate mushrooming of the projectile on striking an object. The whole projectile-including the interior of the aperture is plated'with a thin coating 17 of cadmium. The coating being very thin and the metal cadmium bein sufficiently soft, the mushrooming qualities 0 this bullet are not materially affected, while at the same time the many advantageous results to be obtained from a cadmium coating, as hereinbefore pointed out, are at the same time obtained.

In Fig. 3, there is shown a rifle bullet of the ordinary jacketed type. A jacket 18 of copper, gilding metal, cupro-nickel or ot er metal or alloy, surrounds a core 19 of lead or metal having a high percentage of lead. The whole outer surface is provided with a thin coating 20 of cadmium.

It will be obvious that a similar coating of cadmium may be provided on many types of projectiles other than the three types illustrated, and that like benefits may be obtained from such provision. The term projectile as used in the specification and following claim is used generically-and is to be understood as referring to projectiles generally, including projectiles for ordnance, bullets for small arm rifles and smooth bore guns, as well as ball-shot. The bore coating properties of cadmium are apparently entirely independent of any reaction of this metal with any of the explosive constituents of ammunition, and therefore cadmium coated projectiles may be successfully used in conjunction with ammunition generally. regardless of the accompanying explosive constituents of the ammunition.

Although the invention has been described with reference to cadmium alone as a coating in the form of a plating, it is to be understood that various forms of cadmium amalgams and cadmium alloys may be used as alternatives if desired. It has been found that excellent results are to be obtained from cadmium alone, and that it is unnecessary to complicate the process of coating by introducing other materials.

In the specification and following claim the terms coated with cadmium and coating of cadmium are used as referring to a material containing cadmium, either alone or alloyed with other materials, constituting a portion only, or the entire surface of a projectile; and these terms refer to the application of such coating by any known means, including application by previously formed jackets, bands, etc., or by any suitable manner of depositing the coating on the projectile, or by alloying the coating with the material of the projectile.

It is to be understood that the embodiments of the present invention as shown and described are purely illustrative, and that the scope of the invention is not to be limited thereby except insofar as is defined in the followmg clalm.

I claim: Y A projectile havingbapplied thereto a. coat- 5 ing of cadmium capa le of forming a corrosion preventive film on the walls of a. bore when the ro'eetile is fired therein. WA S N H. WOODFORD.

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