Maybe I am too simplistic.

Get barrel, get GO 7mm-08 gauge, put tape (scotch for tight, freezer for loose) in gun, screw in barrel until it touches the gauge, set nut, check, if full bolt close, add a piece of tape (scotch) if still loose undo nut, repeat until the GO gauge closes almost all the way or all the way, tight on the no go tape.

Add ammo, got shoot.