All of them!
As mentioned, M1 garand, M1 carbine, BAR, really pretty much every us gun from WW2.
Bunch of good original lever guns would be sweet too.
Another random one I thought was cool that I saw in an old catalog my buddy had was an over/under with 2 different calibers. They had a huge list of damn near any common caliber that you could get it in. I don't know why, I just thought it would be neat gun to have. I could never really nail down which 2 calibers though
Here's an interesting twist on a similar concept, not sure how I like the adapters though
https://www.alloutdoor.com/2016/08/...ion-gun-shoot-dozen-different-calibersgauges/