I have taken out more than .008", I can not remember the exact amount, it was from a damascus barreled Bonehill. I always use a wall thickness gauge and check the barrels throughout. I like at east .025" walls. The Bonehill mentioned earlier was over .045" MWT to begin with. Lots of metal to work with and it remained plenty safe, If memory serves on that one I opened the bore up a bit over .012" so it ended up with nearly .040" walls. On most guns cleaning up .0025" on a side will do wonders.

Firearms imports, consignments


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