Depends on how far off the fit is, some need considerable work, many choose not to go that route and just sell the barrel in hopes of getting another that fits better. Others lock up and fit fine, just depends. I think the newer barrels have better chambers on them, bores are still on the large size, but Handirifle had no chamber issues with his, but many have on older barrels, necks that were too tight to be able to chamber the bullets that shoot good in the oversize bore. If I wanted one now, I'd get one fitted instead of buying a used one.

Tim