Only happened once for me, shooting a SAA in 44/40 that my boss loaded for someone else, and asked me to shoot for group. Top strap through the ceiling, 1/3 x 2 of the cylinder into the side barriers at the range. 1/3 cylinder left on the revolver and 1/2 of the case left in the 1/2 of that particular cylinder. What you see was an overcharge, or improper powder selection, I go for overcharge.