A fellow "Fan of Bronze" shared this recently. For those who aren't up on Clark Savage, Jr., this is the machine pistol he and his team use. It fires "non-lethal" bullets (non-lethal from a chemical standpoint, not rubber bullets). The physics are a little fuzzy, of course, but this illustration takes a stab at it.
With this weapon, criminals could be kept alive for their (ahem) humane brain surgery in Doc's secret hospital in upstate New York.