I was going to buy one of the carbines, but decided that the 18 1/2" barrel looked too stubby for me. I took my old 22" barrel and cut it down to 20" and was happy. You could use any factory ammo you want. I'v used 150, 165, and 180 grain loads with no issues. Barrel length doesn't make that big of a difference in the 30-06. You'd lose about 100 fps or so, and that means you'd at least have the same velocity/power as a standard .308 in a longer 22" barrel. A deer doesn't know the difference between a 150 grain at 2900 fps or 2750 fps. Maybe an inch more drop at 300 yds. You'd never be able to tell yourself. Muzzle blast and jump would be the bigger issue, with that short barrel. It will be LOUD. I can tell a differece in the jump between the 20" and a longer barrel too.