US1880235A - Priming mixture - Google Patents

Description

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This invention relates to priming mixtures for ammunition, particularly priming mixtures of the non-corrosive type, such m x tures not only leaving no corrosive residue in the bore of the gun but apparentlw ac tually coating the bore of the gun an adherent protective film which i'evw s, formation of rust even under the most ad =1- conditions.

It has long been recognized that otass um chlorate, the most commonly use oxidizer in priming mixtures, was responsible for the corrosion of gun barrels which occurred subsequent to firing even though the barrel had 35 been carefully cleaned and oiled. Potassium chlorate however, by reason of its high oxygen content, the ease with which it releases its oxygen whenheated and its stabili in the presence of moisture was remarka 1y well adapted for use as a priming mixture oxidizer, and the securing of a substitute therefor was a problem of great difiiculty. y non-corrosive priming compositions have been tried but very few of these have been sufiiciently successful to be actually embodied in a manufacturers commercial product.

Recently, however, carefully prepared and proportioned compositions, using barium n1- trate as an oxidizer have been marketed wlth extraordinary success. In these compositions the content of mercury fulminate is comparatively high on account of the necessity for reaching the high temperature at which barium nitrate yields its oxygen. Priming mixtures containing a large amount of mercury fulminate are undesirable for several reasons. Mercugy fulminate is comparatively expensive an the cost of the mixture is increased with an increase in the fulminate content. Of greater importance, however, is the fact that mercury fulminateis of a poisonous nature and the preparation and handling of mixtures containing a great deal as of fulminate are difiicult and may be in- Application filed September as, 1923. Serial No. 805,129.

jur'ious to the workmen. Mercury fulminate is moreover, highly explosive, and must always he handled with extreme care.

The present invention comprises the discov ry of an explosive which may be substituted for a part of the mercury fulminate in non-corrosive mixtures. The fulminate content being thus reduced, the mixture is cheapened and becomes much more safe-to make and handle. trinitroresorcinate, the normal lead salt of styphnic acidv (trinitroresorcinol) has been found to be most desirable. The'replacement of a partofthe mercury fulminate by lead trinitroresorcinate not only makes the mixture more suitable for handling "andloading but also serves to regulate the combustion of the mixturein such a way as to eliminate certain irregularities which appear to be inevitable in non-corrosive mixtures containing mercury fulminate only as an explosive.

Mercury fulminate detonates under the impact of the firing pin but this action being an instantaneous detonation, and not combustion, does not produce a sustained flame.

For this purpose lead The result is that the temperature may not be raised sufiiciently to effect the proper reaction between the fuel and the sluggish non corrosive oxidizer. Increasing the fulminate content merely serves to increase the force of this detonation, and not to appreciably increase the duration of the accompanying flame, and furthermore the increase in the fulminate" content is productive of pierced and broken cartridge heads due to the excessive momentary pressure brou ht about by the detonation. It has been ound accordin ly, that non-corrosive primers which depen on mercury fulminate alone as a combustion initiator are subject to certain irregularities of performance even when most carefully proportioned and mixed and loaded with the utmost care. These varianevertheless undesirable andplace certain restrictions upon the range of usefulness of such mixtures.

Lead trinitroresorcinate is less sensitive to blow and shock than mercury fulminate but;

its reaction time is much longer, and is accompanied by well sustained flame. This may be due to the fact that the decomposition of lead trinitroresorcinate results in much more free carbon than the decomposition of mercury fulminate. This carbon is burned with oxygen supplied by the priming mixture oxidizer with a hot and Well sustained flame. Furthermore, the presence of the excess of nascent carbon serves toaccelerate gish barium nitrate, and the accompanying heat raises the temperature to the point where oxygen is liberated for the combustion These proportions, however, may be substantially varied. Good results have been secured with mixtures containing as little as 5% or as much as 20% of lead trinitroresorcinate, the mercury fulminate content being varied accordingly, as between the range of 20% and 40%. For example,'the following is a very successful formula:

What is claimed is:

A noncorrosive priming mixture for wet loading into rim fire cartridges having substantially the following composition:

Approximate per cent Mercury fulminate 30 Lead trinitroresorcinate 1O Barium nitrate 29 Lead sulphocyanate 1O Abrasive 20 -Binder 1 JAMES E. BURNS.

the release of oxygen by the otherwise slugj I Per cent. Mercury fulminate 31.5 Lead trinitroresorcinate 5. 5 Barium nitrate 30.5 Lead sulphocyanate 10. 5. Abrasive 21 Binder; i 1 I The mixtures of thisinvention are especially adapted for rim, fire cartridges, into which they are loaded in'a moist condition. A pelletof the moist priming mixture is dropped into the shell, and spun out into the shell rim by a spinning punch. The shell or powder case is comparatively short, and the powder' lies in immediate contact with the priming mixture. Such rim fire cartridges require a priming mixture differing somewhat from that used for center fire cartridges in which. the mixture may be loaded dry and is placed in aseparate-cup which communicates with.- the end of a long powder case through a flash hole. The present invention is thought to constitute the first rim fire mixture containing mercury fulminate and lead trinitroresorcinate, and the appended. claims are to be broadly construed.