I agree with JE Custom, I've crowned and installed muzzle brakes with the receiver still on the barrel. If you can stick it thorugh the headstock in your lathe, like this:
And have either added a spider to the back end, as shown in the picture, or have cross drilled the spindle for support spider bolts, then just do as JE suggests, strip the receiver, indicate it in carefully, and have at it with out unscrewing the receiver from the barrel.
The barrel in the picture is 24" long. It's the re-chambered barrel from my .22-250 LRPV that is set up for crowning. With the spider chuck in place of the 4J the spindle is short enough that I can chamber 19" barrels which is handy. The micrometer carriage stop was borrowed from my 9" South Bend.