Depends on how far you turned it and which direction. The firing pin is notched and the screw keeps the pin in by protruding into that notch. Too loose and the pin could fly out. Too tight and the pin will bind. I have had my pin out a few times to clean the channel and I always just tighten it til snug then back it out a half a turn. I then check that the firing pin moves smoothly by pushing on it with a punch. If you take the screw out be sure to apply a drop of thread locker to the threads to keep it from backing out when shooting.