Abstract: For use in a gun supporting a bullet for obtaining a core sample therein wherein the bullet is received in a chamber in the gun, a retrieval cable connecting between a pair of studs for threading to the bullet and gun, the cable being coiled to enable the cable and heads of the stud to be received in a sacrificial plastic cylindrical housing. An electrical flow path is also provided by means of a conductor optionally positioned adjacent an exploding cap and extending to an electrically isolated ground terminal. The ground terminal connects with ground through a compressed spring extending through the housing for contact against the ground.