US2304037A - Propellent explosive charge - Google Patents

Description

' colloided nitrocellulose the charge or a portion ton . Thomson, Kilmamock, Scotld, and Ed.

tworth, New York, N. Y :1.

t to

Chemical industries ted, a cof Great Britain No Drawing. application April 19,.ll9tll, 8e

, No. 389,462. In Great in 13 Claims.

This invention relates to the manufacture of propellent explosive charges, and more particularly to the provision of gun charges containing a constituent adapted to reduce or eliminate muzzle flash which has also the property of reducing metallic fouling by action of the hot gases on the projectile in the firearm.

The inclusion of a small proportion of certain alkali metal salts in propellent powder charges made from colloided nitrocellulose with or without the inclusion of nitroglycerine or other gelatinisers, Whether of deterrent or non-deterrent nature, is known to have a strong eiTect in reducing the muzzle flash; and, in conditions favourable to the action of the alkali metal salt, the flash may even be suppressed altogether. The alkali metal salts hitherto employed for this purpose, however, have not' been possessed of the property of reducing to any appreciable extent the metallic fouling of the rifled arms in which the propellent charge containing them is fired. Flash reducing compounds moreover tend to cause a falling oil in the smokelessness of the propellent charge.

It is known thatmetallic fouling in rifled arms is reduced by the inclusion in the propellent charge of tin, or lead, or certain alloys or compounds of these metals. One method of employline such a metal or alloy consists in encasing thereof in the metal foil. It has also been proposed to incorporate tin or lead compounds as ingredients during the manufacture of the propellent powder. It has been stated that the muzzle flash produced by the combustion of the powder gases is very considerably reduced when tin, tin alloys, or tin compounds are present in the propellent charge.

It is an object of our invention to provide an anti-muzzle flash type of gun charge having a reduced tendency to cause smoke. It is also an object of our invention to provide an anti-fouling type of gun charge having improved flashless characteristics. ,It is a further object of our invention to produce an anti-fouling type of gun charge having a reduced tendency to cause smoke. It is a still further object of our invention to provide a gun charge having an improved combination of anti-fouling, antiefiash and smokeless characteristics. It is a still further object of our invention to provide a colloided nitrocellulos propellent powder containing within its composition a compound conferring antifouling and anti-flash characteristics chemically compatible with the common ingredients present in smokeless powders and which powder has satisfactory storage properties. A still further object is to provide colloided nitrocellulose powders adapted for automatic firing arms, which powders have improved firing characteristics, and with which no muzzle attachment for the suppression of flash is required.

We have found that these and other objects are attained by the inclusion in the colloided nitrocellulose charge of an antimonyl compound containing a combined alkali metal. The antimonyl compound is desirably one free from halogens. The alkali metal antimonyl tartrates and their double salt with other alkali metal salts are conveniently used, for instance potassium antimonyl tartrate, commonly known as tartar emetic, lithium or sodium antimonyl tartrate, or the double salts of potassium antimonyl tartrate with potassium bitartrate, lithium nitrate, sodium nitrate or sodium sulphate. We prefer, how. ever, to employ tartar emetic. The colloided nitrocellulose propellent powder may be a single base powder or a double base powder, and may include gelatinisers of a deterrent or non-deterrent nature in its composition and may, if desired, be surface moderated. Any of the common deterrents such as esters, nitrocompounds, substituted ureas or urethanes of low volatility may be employed, for instance, di-alkyl phthalates, alkyl glycollates, alkyl tartrates, alkyl lactates, acetates of polyhydric alcohols, dinitrotoluene, mononitrotoluene, diaryl dialkyl ureas, and aryl aralkyl urethanes and aryl alkyl urethanes, may

. conveniently be employed. In the case of double base powders, nitroglycerine or other liquid nitrates of polyhydric alcohols may be employed with or without deterrents.

In putting the invention into eflectwe may introduce an antimony compound into the propellent composition in a uniform manner during the manufacture of the latter, but a uniform distribution is not always essential to the success of the invention. Thus in the case of charges for heavy artillery it is possible to employ as part of the charge an ordinary colloided nitrocellulose propellent powder and as another part of the charge a propellent powder containing a very considerable proportion of tartar emetic. In some cases the tartar emetic may be applied to the surface of the grains of the propellent powder thereby enabling stocks of already manufactured propellent powders to be treated so as to improve their characteristics. In the application of-the invention to propellent charges for small arms ammunition for machine guns and the like, the most practicable methods of introducing the tartar emetic or other antimonyl compound used involves its distribution in a more or less uniform manner throughout the powder. It may be convemently introduced into the composition of the charge before the commencement of the gelatinisation of the nitrocellulose.

The proportion of tartar emetic employed may conveniently be from about 1% to about 5% reckoned on the weight of the total charge. Although increasing the proportion of this compound increases the anti-fouling and flash reducing properties, the compound is not devoid of all tendency to increase the smoke, and it is found that between these limits a particularly favourable combination of properties results.

The invention finds particular application in small arms ammunition for use in machine guns and automatic rifles, the use of tartar emetic containing propellent powders for such ammunition effectively reduces the muzzle flash and ensures effective removal of metallic fouling from the bore of the firearm, and renders unnecessary the use of muzzle attachments for masking muzzle flash. This is an advantage since these attachments frequently give trouble owing to the accumulation of th metallic fouling in them. The colloided nitrocellulose powders containing tartar emetic have storage properties as good as similar powders from which the tartar emetic has been omitted.

The invention is illustrated by the following examples in which the parts are parts by weight.

Example 1 This example relates to the manufacture of a single base rifle powder. An amount of alcoholdehydrated nitrocellulose containing 99 parts dry weight of nitrocellulose of 13.2 percent nitrogen content is mixed with 3 parts tartar emetic that has been finely ground and sifted through a wire sieve having 100 meshes to the limb, British standard specification. The mixture is then colloided by the introduction in known manner of ether containing in solution one part diphenylamine. The colloid is pressed through a die and out. It is then treated for solvent recovery and steeped in hot water, and is finally surfac moderated with 3 parts dimethyl diphenyl urea and coated with graphite.

In a test carried out with a 0.303 inch short magazine Lee-Enfield rifle in which the barrel had been considerably shortened, a rifle powder so prepared gave no flash whatever when fired; whereas a powder made in similar fashion but from which the tartar emetic had been omitted, gave a brilliant flash. An analysis of the metallic deposits from 47 rounds of cupro-nickel jacketed bullets in 0.303 inch short magazine Lee-Enfleld barrels fired with the rifle powder containing the tartar emetic and the same number of rounds flred with the powder from which it had been omitted gave as thetotal weight of meta1 fouling 0.05 gm. and 0.25 gm. respectively. The diminution in the effective bore diameter caused by the metal fouling at a point 20 inches up the barrel.

in the case of the powder containing the tartar emetic was only about one tenth of that observed in the case of the powder containing no tartar emetic.

Example 2 This example relates to the manufacture of a single base machine gunpowder. An amount of alcohol dehydrated nitrocellulose containing 99 parts dryweight of nitrocellulose of 13.2 per cent. nitrogen content is mixed with tartar emetic that sieve having 100 meshes to the inch, British standard specification. The mixture is then colloided by the introduction of ether containing in solution one part of diphenylamine. The colloid .is pressed through a die and out. It is then treated for solvent recovery and steeped in hot water, and is finally surface moderated with a mixture of 3.5 parts dimethyl diphenyl urea and 3.5 parts dibutylphthalate and coated with graphite.

Example 3 This example relates to the manufacture of a double base machine gun powder. 29 parts nitroglycerine are mixed with 65 parts dry nitrocellulose of 13.1 per cent. nitrogen content. The resulting paste is colloided with a solution of 6 parts diethyl diphenyl urea in aqueous acetone and 3 parts of tartar emetic are added during the incorporation of these ingredients, which is car ried out in a mixing machine at about 30 C. The resulting plastic is pressed through a die into cords which are subsequently stoved and reeled into a rope, which is finally cut to the desired grain length. a

The advantages of the invention may be readily appreciated by the following table showing the results of a test carried out in a A; inch Vickers machine gun using a 664 grain bullet having a solid gilding meta1 envelope, the number of rounds fired being 20, in which the results obtained on firing the powder of Example 2 are compared with those obtained on firing otherwise similar powders from the composition of which the tartar emetic has been omitted or replaced by certain hitherto known anti-fouling and anti-flash ingredients. Y

The flrst column of the table indicates the amount of anti-flash or anti-fouling ingredient used in making the colloided nitrocellulose powder for every 99 parts of the nitrocellulose. The second column indicates the amount of copper found by analysis in the barrel residues of the firearm, 'and the third column describes the appearance of the flash obtained. The fourth column indicates the order in which the various powders used approach freedom from smoke.

When antimonyl compounds containing a combined alkali metal other than tartar emetic are used, an amount having an antimonyl content equivalent to that of one to five parts tartar emetic may be conveniently employed for every 100 parts of the propellent explosive.

As many. apparently widely different embodiments of the invention can. be made without departing from the spirit and scope thereof, it must be understood that the invention is not limited base been finely ground and sifted through a wire to to any specific embodiment except as defined in the appended claims.

We claim:

1. A colloided nitrocellulose propellent powder gun charge comprising an antimonyl compound free from halogens and containing a combined alkali metal. I

2. A colloided nitrocellulose propellent powder gun charge comprising an alkali metal antimonyl tartrate.

3. A colloided nitrocellulose propellent powder gun charge comprising tartar emetic.

4. A small arms propellent powder comprising colloided nitrocellulose propellent powder having tartar emetic distributed homogeneously through it.

5. A small arms propellent powder comprising a single base colloided nitrocellulose powder having tartar emetic distributed homogeneously gun charge comprising a double salt of an alkali 20 metal antimonyl tartrate and another alkali me al salt free from halogens.

9.- A colloided nitrocellulose propellent gt charge containing from about 1 to about 5 p cent. tartar emetic.

10. A colloided nitrocellulose propellent powdl gun charge having an alkali metal antimon; tartrate distributed unequally through it.

11. A colloided nitrocellulose propellent powd comprising a deterrent and from about 1 to aboi 5 per cent. tartar emetic.

12. A smokeless colloided nitrocellulose prr pellent powder to the surface of which tart: emetic has been applied.

13. A colloided nitrocellulose powder gun charg comprising an amount of an alkali metal anti monyl tartrate equivalent in its antimonyl con tent to about 1 to about 5 per cent. tartar emeti THOMAS THOMSON. EDWARD WHITWORTH.