Going to a semi-auto will not do a ton to reduce recoil. However, most ARs are equipped with muzzle brakes and that WILL reduce recoil. A 223 in an AR really has zero recoil, in a 308 it will have some but really light. Problem is, you will need to wear earplugs while you hunt or you will lose your hearing. Shooting a muzzle brake with bare ears is NOT something you can tolerate and is not wise. This is one major reason I would never consider a braked rifle for normal hunting.

Rather than going to an AR to reduce recoil, I think you would be better off to either get a 7mm-08 or 243 in a bolt action. 7mm-08 with lighter range bullets is PLENTY for deer and will have very light recoil, 243 has VERY light recoil with any deer load.

If you really want an AR to hunt with, I would get an upper with either of the above cartridges and no brake.