Ammunition Primer

Abstract

A primer for small and medium caliber ammunition which produces a jet-like lame that extends into the propellant bed of the munition. The primer has a primer pellet seated in a primer cup, the pellet including a plurality of centrally apertured propellant sheets and an igniter button of pyrotechnic mix filling the central apertures, and an anvil secured within the cup and having a conically shaped central portion embedded in the igniter button.

Description

This invention relates to primers and, more particularly, to primers for small and medium caliber ammunition.

It is an object of the invention to provide a primer that will accomplish propellant ignition with the use of hot gases, eliminating the need for metal powders or other hot particles to carry heat downstream.

Another object of the invention is to provide such a primer which is ashless and will minimize barrel erosion in associated weapons employed to fire ammunition containing this primer.

A further object of the invention is to provide such a primer having minimal brisance, thereby enabling reductions in cup wall thickness and firing pin energy.

These and other objects, features and advantages will become apparent from the following description and accompanying drawing in which the sole FIGURE is a longitudinal sectional view of a preferred ammunition primer embodying the principles of the invention.

The primer, shown generally at 10, is particularly useful in small and medium caliber ammunition arrangements. The primer is formed of a relatively thin-walled cup member 11 in the bottom of which is seated a primer pellet that includes a plurality of propellant sheets 12. Each propellant sheet has a central aperture 13 of predetermined size and location and is capable of being positioned in uniform alignment to receive an igniter button 14 which has a portion that fills the central openings in the propellant sheets upon assembly. The button has a head portion that overlies and contacts the adjacent surface area of the outer propellant sheet. When the conically shaped anvil 15 is press-fitted into position within the sidewalls of the cup 11, the anvil nose portion 16 is embedded into the igniter button material 14.

Both the anvil 15 and cup 11 are formed of brass material. Preferably, the propellant sheets which deflagrate under controlled high pressure conditions are composed of nitrocellulose, 52.15 percent by weight; nitroglycerine, 43.0 percent; diethylphthlate, 3.0 percent; potassium nitrate, 1.25 percent; and ethyl centralite, 0.6 percent. The igniter button is preferably a percussion sensitive pyrotechnic mix composed of lead styphenate, 37.0 percent by weight; tetracene, 4.0 percent; barium nitrate, 32.0 percent, PETN 5.0 percent; antimony sulfide, 15.0 percent; and aluminum powder, 7.0 percent.

When a firing pin strikes the primer cup base and crushed the igniter button against the anvil, the highly reactive propellant sheet material is initiated by the igniter button to produce a controllable high velocity jet-like flame that extends into the propellant bed of the ammunition. The burning rate of the propellant sheet material is controlled by the size of the vent in the web between the primer cavity and the case chamber in the munition employing the improved primer. Thus, a regulated high primer burning rate can be achieved with high pressure to produce the jet-like flame. As a result, propellant ignition can be obtained with hot gases only, and the need for metal powders or other hot particles to carry heat downstream is eliminated. In effect, an ashless primer is employed which will leave a clean barrel, especially desirable in automatic weapons, and minimize barrel erosion. Also, the size and weight of the primer is reduced, as well as the required firing pin energy, due to the use of relatively thin primer cup walls made possible by the significant reduction in brisance.

Various modifications, changes or alterations may be resorted to without departing from the scope of the invention defined as follows.

Claims

We claim:

1. A primer for small and medium caliber ammunition comprising,

a primer cup,

a primer pellet seated in said cup and including a plurality of propellant sheets each having a central aperture therethrough in substantial alignment with each other and an igniter button of pyrotechnic mix filling said central apertures, and

an anvil secured within said cup and having a conically shaped central portion embedded in said igniter button.

2. The structure in accordance with claim 1 wherein said igniter button has a head portion overlying and contacting an adjacent surface of one of said propellant sheets.

3. The structure of claim 2 wherein said propellant sheets are composed of, by weight, 52.15 percent nitrocellulose; 43.0 percent nitroglycerine; 3.0 percent diethylphthalate; 1.25 percent potassium nitrate; and 0.6 percent ethyl centralite.

4. The structure of claim 3 wherein said igniter button is a percussion sensitive pyrotechnic mix composed of, by weight, 37.0 percent lead styphnate; 4.0 percent tetracene; 32.0 percent barium nitrate; 5.0 percent PETN; 15.0 percent antimony sulfide; and 7.0 percent aluminum powder.