It's weird, Mike.
A Beretta BM-59 barrel will thread, and tighten properly, into a USGI M1 Garand receiver, no problem. Don't forget, Beretta got all the Winchester M1 Garand tooling after WWII, and they were making those Beretta M1 Garands until such time as they started production of the 7.62mm NATO BM-59, basically building an M14-type rifle from the parent M1 Garand, with an emphasis on parts commonality. (is that a word?)
In doing so, the Italians beat us to an M14-type rifle many years ahead of our own M1 Garand derivative, known as the M14.
I've also seen BM-59 gas cylinders screwed onto M1 "Tanker" Garand barrels, so I'd have to state that even though they were made in a metric country, they stayed with inch-pattern tooling. There was a big export market out there for the BM-59, and Beretta wasted no time making display packages for prospective customers of the rifle. I remember looking at one of the BM-59 promotional posters, and how they highlighted the use of M1 Garand parts in the production of the BM-59. Not a bad selling point, considering how plentiful M1 Garands were at the time, as well as M1 Garand spare parts.
My own Nigerian model BM-59 was built on a Winchester M1 Garand receiver, with everything else stamped "P.B."
What a lot of people don't know, however, is that an outfit in the Phillipines is marketing a shortened, box-magazine-fed conversion of the M1 Garand on the international market. I found it through Jane's, of all places.