At under 6 feet (probably less), one shot of No. 4 steel load is about the equivalent as emptying a .38 into someone.
The pellets have not spread and are a solid lump going the somewhere around the speed of sound.
You said that wouldn’t do much to a person.
You are incorrect. It will blow a giant hole in a persons face.
I suggest that bigfootbob get a roll of brown wrapping paper and a sheet of quarter inch plywood, Pin the paper to the plywood as a target. Then at 30ft 20ft 10ft 5ft fire a standard choked-for-duck 12ga shotgun loaded with number-6 shot and look at the patterns and penetrations on the target. I’ve seen it done. Quite impressive.