12-08-2012, 07:18 AM
I couldn't tell you about YHM forearm since I have never used one, I would call them if no one here has the answer. I assume you are talking about the barrel threads , I use Loctite C5-A copper based anti-seize on my barrel threads. I also coat the outside of the barrel extension that fits into the upper receiver with blue loctite. Be careful not to get any on the threads. There is a good thread on this forum on how to assemble your upper AR if you need the information.

