Huh, never heard of such a thing. Seems like forcing the larger upper body of the shell through the smaller barrel just wouldn't be a good idea. Looks like it works though. I'd like to see it done against several 2x12's sandwiched together to see what it would do compared to a slug. I bet that would create a helluva wound channel in a bear, and probably ruin a lot of good deer or elk meat. Probably less than legal too, I'd imagine.