A fastener driving tool includes a power source including a cylinder, a piston with a driver blade reciprocating in the cylinder, a tool nose associated with the power source for receiving the driver blade for driving fasteners fed into the nose, and a magazine housing a supply of the fasteners. A magazine feeder mechanism is associated with the magazine for sequentially feeding fasteners into the nose, and the feeder mechanism includes a reciprocating feed piston. A conduit is connected between a port in the cylinder and the feed mechanism for diverting combusted gas for activating the feed piston. The port is disposed in the cylinder a specified distance below a piston prefiring position, the distance being reflective of a delay of activating the feed piston until the drive piston finishes a driving stroke and begins a return to the prefiring position.