04-22-2021, 08:18 PM
mv1arms Wrote:I think the inside was ceracoted, ya. I probably should have requested that be left alone.Um, irrelevant.
BCM uppers (and Noveske, VLTOR, JPE) are machined to require thermal fitting.
If you are getting one, you will be thermal fitting, and using any simple liquid to chill the barrel is a waste of time.

