Which is better: Cerakoting/Gunkoting the barreled action before or after bedding or does it matter? TIA

I always coated my actions after bedding them. Most bedding compounds shrink slightly when cured and the coating helps fill that void. Win-win. And never had any issues.

I always do it after.

After coating but be very diligent about degreasing after bedding to remove all traces of the release agent. Brownells is easiest to remove, wax takes more work, silicone is next to impossible. I avoid silicone release agent for this and other reasons.