If you ever remove ar barrels! - Aero Precision .308 BAR Shim Pack

If you pull apart your .308 up to removing barrels or plan to. You should keep a set or 2 of these on hand. Some barrels need them some do not. If your barrel is shimed removal can mess thin shims up. Having all this kind of little stuff on hand has simply made messing around with configurations way more possible.
Sucks when you just about have your new build or replacement complete just to find you have to order parts.