I watched a guy shoot a 3.5" Win HV from his NEF, he had just got the gun and was just goofing around at 25yds.
He was sitting on a cooler in his yard when he touched it off. It rolled him right off that cooler and about knocked him out.
He wasn't a big guy but still, that's a bit more hit than I want to take.
There is a 3.5" 12 gauge in a local shop but it has a weight in the back like a 10 gauge, his did not. I think his only weighed around 6lbs.