Recoil?
#3
I would agree. Bullet weight has more to do with recoil than velocity really. I shot my buddy's 12 gauge 870 about ten times with slugs last weekend and my shoulder is just now in the right place! The slugs where probably only going 1200-1300 fps, but over an once of lead hurts no matter what. Yet another reason why front stuffers are better than slug guns!