Agreed I would buy a 6.5 x 55 headspace case though,, I would remove one of the bullets, and make sure that you’re not smashing those bullets into the lands because you have no idea what gun that was loaded for it’s factory ammunition I’m sure you’re fine, but when you go from really old stuff to more modern guns. You’re run into issues but it looks like all your stuff is old so I probably won’t be too concerned about it but if you have any problems closing the bolt or tightness I would be weary and check that