Sorry, I'm another that can't see why/how you would have an issue with the recoil, from a .223/5.56, especially the AR platform. Its literally a springy feeling, *SPROING*.

Also, a .223 bolt action, is going to have significantly more kick, than an AR. All the force of the recoil, is pushing back into your shoulder. The only dampening, really... is a recoil pad in that case. My Stevens .308, now that kicks like a horse, kicking thru your shoulder. Bipod helped, considerably, but still. Not a fun rifle to shoot (and expensive), for more than a few groups.

However, I do see the need for a buttpad on the ARs, just simply for shoulder seating/placement and retention... I've got a Tapco Intrafuse buttpad ($10), that just slips right on. Its a nice thick, pad... though not the softest rubber. Its still pretty substantial and has a bit of a curve on the back. It feels and seats, real nice up against where, I like to hold my rifle.

EDIT: Yeah, I know... the .308 isn't that big a cartridge. After having my chest cracked open, the wrong type of big rifle recoil, is very unpleasant. I do not like shooting bolt actions anymore, because of it.