any long action (or even short action) round. any of the 06 family including the 270. if you have a smith that can open up the bolt face, then you can use any of the 284 family as well as non-belted mags. no short mags, no 223 size/family. you could make it a 243/260/308 family stuff but that is more short action, you wouldn't need a long action, but you COULD use it for that.