There's some law that says breechloaders can be sold in the USA with bores larger then .51 cal because of some stupid ATF regulation. Even Bowen had to get a special license before he could make his 577 revolver. Now I know we have and sell 12 gage rifled guns here in the USA for use with slugs, and I am not sure how it gets around the ATF reg, but maybe there's a way to do it. If one was made for brass shells and had a rifled bore it could be legal.
Anyone know more about this than I do? Some one has to..........I know very little about them