Ironic you brought that up. A couple of us were talking about machining out chambers and "inserts" came into the conversation. I had just cut out a chamber to "fire form" a 22.250 into a 22.250 Ackley improved and one of my buds wanted to borrow the cutting tool. .06 to 308, phewww, major difference in case length (base to neck dimension and total). I would be pressed to purchase a new Shilen barrel alreay machined for the desired caliber.
Just one man's opinion.