One rather inconvenient truth for some of the M1 rifle and carbine parts assemblers of today is that FN was actually contracted by the U.S ... the U.S. military contracted with FN to repair, ...

All World War II .30-cal. M1 Carbine ammunition was manufactured with non-corrosive primers. If the barrels were not routinely cleaned, there were no corrosive primer salts to ruin the bores.