If you want to decock a Glock after firing it, just let go of the trigger. One of the brilliant and unique features of the Glock is that it combines the best attributes of a SA/DA and DAO pistols. The first shot on a Glock is a moderately-long trigger pull; not as long as many DAO's, but longer than a 1911. If the trigger is not released fully after each shot, however, follow-on shots may be fired with an extremely short trigger pull as the gun will remain cocked between shots. Releasing the trigger fully, however, will decock the gun to the point that the striker spring no longer has enough energy to fire a round.