I use a barrel vise when changing barrels My M10 had the problem that when tightening the barrel nut, the recoil lug and action turned, changing the headspace. It is possible to compensate for this by controlling the barrel nut tight start position, and I can hold the action still with a big screwdriver across the port of the barrel while tightening the barrel nut.
I thought about this, and concluded that something was "catching". I examined the action-end of the barrel nut, both sides of the recoil lug and the front end of the action, and removed any distorted bumpy-like protrusions on all four surfaces.
I REMOVED ONLY DISTORTED SMALL BUMPS-NOT ANY BASE MATERIAL!!! The barrel nut had the most bumps/distortions.
Then, with Syl-Glyde silicon grease on the end of the barrel nut, both sides of the recoil lug and the front of the action, I put the gun together and headspaced it twice. When I tightened the barrel nut, the recoil lug/action didn't turn.
joe b.