A machinegun pistol switchable between semi and full automatic modes by an operator holding the gun in a natural two-hand grip. The gun includes a bolt (20) and a firing pin device 22 that each slide longitudinally, a trigger assembly with a primary sear (28) that is depressed by the trigger for semiautomatic operation, and an auto control member (34) that can be depressed into the frame (16) to switch to full automatic operation. When the control member (34) is depressed, it connects a secondary sear (36) with the primary sear. The bolt carries a cam (40) that can depress the secondary sear (36) when the bolt moves forward, to thereby repeatedly depress the primary sear (28) when the two sears are connected during automatic operation. The control member (34) lies on the right side of the gun, forward of the trigger (14), so that when the left hand is used to also hold the gun, the fingers of the left hand can feel and depress the control member. In another embodiment operation of the control member (34) moves the secondary sear (36) into and out of the path of the bolt cam (40).