Use a full circle disc of soft aluminum as a shim, not washers. I rough out the center hole with a big hole saw in a drill press when making a spacer, then finish off with a half-round file in a vise, or just spin the disc up on the lathe and machine the final diameter. I'd be a lost ball in high weeds without a machine shop a few steps out the back door, for both gunsmithing and hotrodding!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!