OK... someone has to say it. A10 came close...
What recoil?
Seriously, I just spent 4+ hours this Monday, putting 430 rnds downrange firing a Mini-14 and AR15. Shoulder never got tired, or sore... and I've had freakin' open heart surgery. No bruise, nor tenderness afterwards, either.
Of course, if shawn explained your situation, please disregard. Firing those two weapons, I certainly do notice a difference in the way they shoot/handle. The "recoil" is completely different, but my AR benefits from a muzzle break and is a bit heavier. To me, they both feel like springs pushing back against my shoulder. The Mini tends to walk up more, if not paying attention.