First you need access to a lathe that has a big enough hole in the spindle to accept the receiver, then you need to make a tapered sleeve set to clamp / hold the barrel in the chuck concentrically. Then you clamp it all in a four jaw chuck, or keep clamping and rotating, and clamping and rotating with a three jaw chuck, (lazy mans way!) until you get it zeroed out... Remove the snug fitted rod out of the barrel that you used for the dial indicator and walla!!! Re-cut your crown with what ever tool fits your fancy!! By the time you get this far, you'll definitely know which tool to use... Best to all, til...lat'r....GT
Oops! Almost forgot? You're most certainly going to have to know how to run a big lathe.. (I know, just like a small one!) Or have a good friend that knows what you don't!!!