I ordered a 762x39 barrel from H&R today I also ordered a 762x54r reamer from clymer . I plan on reaming out the barrel to 762x54r. I have been shooting this round for years now and i like it. has anyone else done this and how dose it shoot? Most of my old mosin nagant rifles can shoot 4" groops at 100 yds this is good for a rifle and ammo that is about 70 years old, at least in my book. I cant wait to find out how it shoots in a brand new barrel. Anyone who has changed the cal. in a handi I would be for ever in your debt if you would share your wisdom. the only rifle i have ever chambered is a mauser. it went very well and i want the same for this. thank you