I have no doubt that at close range #8 will ruin your day and knock the perp off his feet to be sure.
Number 2 steel shot on the other hand will drop a man at 200 yards, closer and we don’t even want to talk about it.
I’m thinking of getting a rifled slug barrel and a scope for some distance practice.
From what? The muzzle crack? Even though Steel doesn't deform like lead, it still isn't going to hold any kind of pattern over 100 yards and the velocity will be so slow, I'll bet the sound gets there first.