If it doesnt change anything then the hammer has been opening the valve and slamming against the valve retaining screw. It sure could be the problem if air is getting dumped out of the valve/barrel because of the hammer setting on the valve stem. I would do this:
1. Look for leaks
2. Change springs out (valve med/soft, hammer soft)
3. Set main reg to 275psi ( and then sweet spot it)
Best half of the "Last Minute Men"