1. Apparatus for controlling the sequential firing of a number of pyrotechnic devices for simulating gunfire in response to trigger signals generated by operation of the gun trigger, comprising: a D.C. voltage source; a connector for receiving said trigger signals; a stepping switch including a number of output contacts individually providing a firing signal for a respective one of said pyrotechnic devices, a center terminal connected to one terminal of said D.C. voltage source, a rotating contact member for sequentially interconnecting said center terminal with a respective one of said number of output contacts, and coil means for rotating said contact member; key means interconnecting said connector and said voltage source with said coil for actuating said apparatus, said key means having an operative and an inoperative position and including first, second, third and fourth switch contacts, said first, second and third switch contacts are open and said fourth switch contact is closed with said key means in said inoperative position, said first, second and third swiTch contacts are closed and said fourth switch contact is open with said key means in said operative position; an additional output terminal; means for manually advancing said rotating contact member, said fourth switch contact connection said one terminal of said D.C. voltage source to said coil means with said key means inoperative; a first indicator for indicating said operative and inoperative positions of said key means; said first switch contact connects said first indicator to said D.C. voltage source terminals, said second switch contact connects said additional output terminal to the other terminal of said D.C. voltage source, and said third switch contact connects said coil means to said connector with said key means in said operative position; whereby said contacting member is rotated successively to a different one of said number of output contacts in response to successive trigger signals.