Priming mix

Abstract

An improved priming mix of the type including an initiator, fuel, and oxidizer, and pyrotechnic component. The improvement being the inclusion of between about 3% and about 20% propellant superfines, the superfines comprising particles less than 100 μm.

Description

CROSS REFERENCE TO RELATED APPLICATION[0001]This application claims priority to prior provisional application Ser. No. 61 / 226,496, filed Jul. 17, 2009, the entire contents of which are incorporated herein by reference.FIELD[0002]The present disclosure relates to priming mixes or priming compounds, and in particular to priming mixes with improved sensitivity.BACKGROUND[0003]The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.[0004]Priming mixes or priming compositions are used in ammunition cartridges, including both center fire and rim fire, shot shells, and loads for power tools and power actuated devices to initiate the combustion of the propellant in the cartridge or shell. The priming mix is disposed in a priming cup at the back of the cartridge or shell. Ignition of the primer is initiated by the impact of a weapon's firing pin on the cup. This mechanical energy deforms the cup, compressing the ...

AI Technical Summary

Benefits of technology

[0009]Generally, embodiments of the present invention provide a priming mix with improved sensitivity. In accordance with a preferred embodiment, an improved priming mix of the type including an initiator, fuel, and oxidizer, and pyrotechnic component is provided. The improvement being that the composition comprises between about 3% and about 20% propellant superfines, and more preferably, between about 5% and about 8% superfines. It is believed that the superfines act as a fast fuel that bridges the reaction between the primary explosive and the pyrotechnic mixture (i.e. the fuel and oxidizers) more reliably than the conventional fines due to its larger surface area. These superfines are preferably through −140 mesh, and more preferably through −250 mesh. Preferably all of the particles have a diameter less than about 100 μm, and preferably at least 80% of the particles have diameters less than about 80 μm, and at least 50% of the particles have diameters less than about 40 μm. In one embodiment, these superfines have a median diameter of between about 23 μm and about 28 μm.

[0013]While propellant fines have been used in priming mixes in the past (see, e.g., U.S. Pat. Nos. 4,963,201, 5,466,315, 5,417,160, 5,547,528, 5,610,367, and 5,831,208), these fines have typically been finely divided propellant made up of nitrocellulose and nitroglycerin (e.g. 60% nitrocellulose and 40% nitroglycerin). However these “fines” have typically been an order of magnitude coarser that the superfines used in accordance with the principles of this invention. Conventional fines range in small particle sizes from about from 0.011 inch to 0.018 inch (280 μm to 460 μm) in contrast with the superfines, which the inventor has discovered improved the sensitivity of priming mixes without adversely affecting reactivity.

[0014]Embodiments of the priming mix thus provide improved sensitivity while maintaining shelf life, reactivity, and safety.

Problems solved by technology

This mechanical energy deforms the cup, compressing the priming mix and generating heat, causing the priming mix to ignite.

Merely increasing the reactivity of the priming mix is neither sufficient nor desirable, because it could increase the incidence of accidental firing of the cartridge or shell.

This primary explosive in almost all cases must be modified because it is too powerful or its velocity of detonation is too high.

Images