After the war the Navy converted several thousand Garand's to .308 and the Berreta BM 59 is nothing more than a .308 Garand adapted with a detachable box magazine. Also, the BAR was converted to .308 and widely used up to the early years of the Vietnam war. On top of that, nearly all the countries we supplied with surplus weapons converted them to NATO standard 7.62 X51.
Parts kits for the BAR when you can find them, are generally available in either caliber and Classic Arms offers M1 clips for 30/06, .308 and .243.