Abstract: In an automatic rifle which has been converted for non-military purposes to be semi-automatic by the removal of parts that allow its automatic function, additional suppressing elements are provided to ensure that the interruptor remains depressed until the bolt carrier fully passes the striker catch before the striker catch is engaged by the interruptor. This prevents premature connection of the striker catch and the interruptor, which could prevent sufficient striker spring pressure so that the next round can be fired. In one embodiment the trigger mechanism is fitted with an additional suppressing element (10) formed as a side push plate 7 on the bridge (6) of bolt carrier (5).