Quote Originally Posted by ireload2 View Post
1/2" on the OD of the shoulder translates into about .007" in headspace increase.
I understand what you are saying but as the barrel and the receiver are probably from two different manufacturers, there is no way to tell (without checking) if the shims will affect the headspace or not. Barrel shank could be longer or receiver shorter or vise versa. Add to that a bolt not original to either and it's a crapshoot.