Thanks Santee,
You might see from my avitar, that I owned an 1862 Gatling Gun. (sold it a few years ago)
It was a six barreled percussion gun, using pistol primers for ignition in a barrel "sleeve" (aka. cartridge) loaded with loose powder and a round ball, much like a percussion revolver cylinder..
Gen. Burnside bought 12 Gatling out of his own pocket at $1k each. these were set up outside the Richmond, VA. but never used in combat. The USN also bought 3 guns . I have seen period photos a USN Monitor on the deck.
My best ,
Blair