i have done what buttstock is planning to try. i have epoxied with acraglass gel the barrel into the reciver. i actually roughened up the barrel extension so the epoxy will stick and used release agent on the reciver. after curing you will end up with an epoxy shim stuck to the barrel that will act as a spacer. as long as the mag tube nut is tight it will reduce much of the play and helped out alot.
