Several years ago, my friend Joe Lozen had an opportunity to fire an original Hotchkiss Revolving Cannon. He kindly sent me this clip – it is the only footage of one of these actually firing live ammunition (note the recoil) that I am aware of. Thanks, Joe!
You can also see some video of US military drill and blank firing from the Fields of Thunder Museum here:
These cannons have a cluster of 5 barrels that rotate, chambered for 37mm (1.5″) shells. For more information on the design and history, see my full video: