Percussion-electric primer and radiation shield

Claim 1

In a cartridge having a base with a central longitudinal recess and a counterbore coaxial therewith defining a rearwardly facing annular surface therebetween, said cartridge having a percussion-electric primer comprising: a cup containing an electrically sensitive primer mixture, said cup having imperforate sidewalls formed into an integral wall at a rear end thereof, said sidewalls having a forward terminus defining an opening for communicating gases generated by said mixture with a cartridge contained propellant, said integral rear wall having a central aperture therein, a rimfire cap having a hollow shank and a peripheral flange with an annular cavity therein in communication with said hollow shank, said flange having a forward peripheral surface aligned with said cartridge base annular surface for substantially restraining forward relative movement therebetween upon impact by a firing pin on said flange, said hollow shank being secured within said cup rear wall aperture in fixed spaced relationship therewith, a percussively sensitive primer mixture positioned within said flange annular cavity, said electrically sensitive primer mixture positioned within said cap hollow shank in contact with said percussively sensitive mixture, and an electrical insulator positioned within said counterbore circumferentially around said rimfire cap, said insulator extending between said flange forward peripheral surface and said cartridge base annular surface with a portion thereof positioned intermediate said cap shank and said cup rear wall aperture, said insulator being arranged to insulate said cap from said cup and base so that a voltage applied between said cap and said base will initiate said electrically sensitive primer mixture and ignite said cartridge propellant.