order to pass into either one of the two circular shaped second and third control cams 125 or 126 a deflector or switching element for deflecting the cam follower roll 148 from the first control cam 124 into either the second or the third control cam 125 or 126 is here no longer required the arrangement for radially displacing the cam follower roll 148 as mentioned hereinbefore is structured in a manner as described hereinafter a gas pressure operable piston 133 is present in this sixth embodiment just as in the fifth embodiment described hereinbefore with reference to fig2 and 26 of the drawings an actuating mechanism or actuating lever 150 possessing a cam 151 cooperates with the gas pressure operable piston 133 as will be seen in fig2 this cam 151 abuts against the cam 134 of the gas pressure operable piston 133 as mentioned hereinbefore when the gas pressure operable piston 133 has not been displaced under the action of gas pressure into the position as shown in the upper portion of fig2 a latch or pawl 152 is linked for pivoting about an axis or pivot shaft 153 at the actuator lever 150 a first idle latch or pawl 154 comprises a first arm 155 which as shown in fig2 engages with the already mentioned latch or pawl 152 and a second arm 156 cooperating with the cam follower roll 148 the first idle latch or pawl 154 is mounted for pivoting about an axis or pivot shaft 164 in the weapon housing 133 the.