Abstract: Improved apparatus for perforating a subterranean formation penetrated by a well bore comprised of at least one encapsulated shaped charge held in the well bore adjacent the formation by a charge carrier optionally selected from a wire carrier or a metal strip carrier. The encapsulated shaped charge includes an ignition end and a capped discharge end, the ignition end having an extension providing cavities for containing opposed portions of a pair of wires. The capped discharge end includes a threaded extension whereby the encapsulated shaped charge can optionally be threadedly attached to a complementary threaded opening in a metal strip carrier. A wire carrier adapter nut is threadedly attached to the capped discharge end extension which provides cavities for containing opposed portions of a pair of additional wires of a four-wire carrier.