You didn't say which adjustment screw but both seem to have detents. Sounds like the detent is not there. Could be several things. Xould be worn or broken.. Will have to be taken apart and replaced. Parts should be available from the manufacturer or GunsPartsCorp. If your uncomfortable with taking the sight off, a trip to the smith is in order. The adjustment screw should not be moving as the weapon is fired or anytime unless it is moved..
