In my foolish stupid youth, my cousin and I removed the shoulder stock from a 12 gage pump shotgun, and held on to the threaded stud, sort of like a pistol grip. I think the stud was 1/2 inch diameter, and about 3 inches long. My cousin fired it with one hand, and the screw threads drew blood on his palm. I wore leather gloves, but it was still quite punishing.