Quote Originally Posted by Graves View Post
I think aims has the 5.45 uppers. If you want some more power I think the 6.8spc is a great round between the .223 and the .308

+1 on the 6.8.

What else is there? Off the top of my head:
.22LR
.223
.243
5.45mm
5.7mm
6.5mm
6.8mm