I bought a used Dan Wesson M15 a couple years back that has always had the bbl/ cylinder gap set too tight, ~0.002”/0.003” as best I can tell. This causes the gun to start to lock up after 20/25 rds due to heat and carbon buildup which I suspect is the reason the gun was originally sold.

I’ve been trying this afternoon to reset the gap to somewhere between 0.005”/0.006” using the factory supplied wrench and a set of automotive feeler gauges and have run into a problem. As per You tube and forum instructions I have loosened the shroud, turned out the barrel, placed a feeler in between the barrel and cylinder, screwed the barrel in to just touching the feeler and replaced the shroud and tightened the muzzle lock nut. So far so good. Now a check shows the barrel moved in a few thousands when I snugged the lock nut and the gap is again somewhere around 0.002”.

I’ve tried leaving the desired feeler in place and snugging the nut hoping it will act as a stop, no luck. I still get movement of the barrel and a too tight gap and a tightly pinch gauge.
The movement appears to occur during the last 1/2 turn of the nut when snugging it down. I don’t think I’m over torquing the nut it’s not much more then finger tight when movement starts and I’m not bearing down on the nut tightening it

Has anyone had any experience with this? Any tips to help keep my sanity and preserve a nice revolver from a hard meeting with my basement wall?
Have I mentioned I’m frustrated?