So now I have a few threaded barrels and while my 22 hosts have proven to be a non-issue as both have a large shoulder they lock up to. Every one of my centerfire pistols will not keep a thread protector on. Does anyone have a good option that wouldn't gunk up the threads? (aka no teflon tape or loc-tite please)

Thin o-ring?

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ETA: oops you said you're worried about the "thread protector" so forget most of what's posted above ... I never shoot with the thread protector on the barrel and that has solved all my problems w/r/t thread protectors coming loose.

You could cut the thread protector in half to make two skinny thread protectors out of the one then tighten the two skinny protectors against each other and that would probably keep them in place.

Or get an O-ring as suggested above or get a Nord-Lock or a split washer but DO NOT use the washer with the suppressor.

I know on the FNP/FNX this was an issue. most of the guys bought these o-rings from McMaster. just stick one on there, screw down the protector and be done with it. I installed one when I got my FNX 45 and haven't had it come loose.

http://www.mcmaster.com/#9263k296/=qvnt63

just get the size that's appropriate for your caliber and be good to go.

Thank you speedy, that sounds like a fix. Does anyone have the P/N for viton o-rings that would work on 1/2x28?

i also need 9mm oring size please

My 22/45 lite came with a wave washer to hold on the thread protector.

Granger makes a spring washer/ wave washer that is a good replacement for the 1/2 28 thread size. You might check them for the dimensions you need.

Teflon tape for pipe threads from Home Depot won't gunk up anything.

I use a 1mm O-ring, 10mm ID on 1/2-28 threads with thread relief.