air plug in position and to stop the link from returning the firing pin and the air plug after the striking action of the hammer and movable by a counterweight set to release the link for stopping a compressed gas from flowing out of a magazine into a bolt when the counterweight set is moved along oblique sliding rail portions of sliding rails in the submachine gun application_number US 201113300687 A description referring to fig1 a toy submachine gun is shown wherein the toy submachine gun comprises a gun body a having a magazine holder a 1 for holding a magazine b and two sliding rails c being bilaterally and symmetrically arranged on the inside wall of the gun body a in this embodiment as shown in fig2 each of the sliding rails c is a sliding grooved rail formed on a respective plat member and affixed to the inside wall of the gun body a each sliding rail c comprises a horizontal sliding rail portion c 1 and an oblique sliding rail portion c 2 backwardly and downwardly extended from one end thereof namely the rear end of the horizontal sliding rail portion c 1 the toy submachine gun further comprises a firing linkage mechanism f which comprises a hammer 1 an air plug 2 a bolt 3 and a counterweight set 4 the hammer 1 comprises a base 11 pivotally mounted at the inside of the gun body a.