The present invention discloses a 03 type
rifle automat, comprising a
piston sleeve, a
piston rod, a
piston spring, a gunlock frame, a gunlock and a return spring, wherein the piston sleeve is connected to an extract opening above a
gun barrel; the
piston rod is disposed in the piston sleeve; the piston spring is disposed on the
piston rod between a piston disc at a front end of the
piston rod and a spring seat disposed on the
gun barrel; the return spring of the piston rod is disposed in a spring hole of the gunlock frame; the other end of the return spring is disposed on a spring seat at aninner wall of a
rifle cartridge receiver; a step through hole is disposed at the bottom centre of the spring hole of the gunlock frame; an extension rod connected to a pushing face of the piston rod passes through the through hole; and a
tail end of the extension rod is provided with a limit weight for limiting the
recoil stroke of the gunlock frame. A locking lug radially projected at the front end of the gunlock is switched and paired with a locking tooth at the
tail end of the
gun barrel. The automat uses a
recoil force of a piston
assembly to neutralize the redundant
recoil after a gunlock
assembly is recoiled in place, and the recoil
stroke is compressed. Under a condition that the gun length is determined, the length of the
cartridge receiver can be shortened, so that the gunlock iscompact and the weight is reduced; or the length of the gun
barrel is increased, so that the initial speed of bullets is increased; a gun body is stable during
shoot, and the shooting average of a running fire is improved.