As OldGrump said, no problems if the guns are sound.
My M1 is from 1943 and I have shot WCC 41 ammo in it. Now I wish I hadn't shot the WCC 41 because of collector value.
I'm stoked that I saw this thread! Found a stash of over a thousand 9mm rounds at my dads but wasn't sure if it was safe.. I may prefer to shoot .45's, but considering how super fun it is to try and get ammo here in California I've got no problem taking them off his hands!
