A welding gun power pin for attaching a welding gun to a power block of a welding system. The welding gun power pin includes a generally cylindrical pin body, and insertion stop member, and a withdrawal stop member which defines a withdrawal stop member length dimension. A channel extends into the outer circumferential surface of the pin body, generally separates the pin body from the withdrawal stop member, and is adapted and configured to accept a generally rigid projection member therein, whereby to mechanically resist withdrawal of the welding gun power pin from the remainder of the welding system. The channel defines a channel width dimension which has a magnitude that is less than the magnitude of the withdrawal stop member length dimension.