Tut, buy a Manson wall thickness gauge from Brownell's for about a hundred bucks and start striking. If one side is thick, take more from that side. If you're doing you own striking, you need the Manson gauge. If you want to use my Manson gauge to get a feel for it, let me know. My 6 1/4 pound Sauer ten gauge bird gun scares everyone who looks at it, but the barrels measure in the mid thirties. Figure that one out. Murphy