I am trying to organize my CMP parts kit so when I have the cash I can get the build completed. I am on the fence about used GI bolts and barrels. I am wondering even if I do buy a good condition take off barrel, can an armorer have issues headspacing? Does a bolt reach a point where headspacing it to a barrel can be an issue? I would like to keep the rifle as GI as possible, but with the new LRB, and 7.62 bolts it may not be worth the extra money to fork out for USGI. Criterion barrels are more money, but if i get burned on a take off barrel I would lose a lot more than the extra cost. Anyone with good and bad experiences? Thanks.