Since the gun is, as I think most of us believe, a rail gun, does it need traditional propellant? That is to say, if we're launching it with magnets, does it need gun powder? I suppose not, and that said, what if there's more than one round in a cartridge? In a neat little line, the firing pin strikes the back, but instead of igniting a propellant, it pushes all rounds forward one position, like croquet.
(drawing not to scale)
But that doesn't explain the muzzle flash, or how the firing pin can push any rounds past the first one.
Hmmm.
Maybe there's some kind of gas behind the last one? But then it all gets used up on that first round. :confused
Maybe there's a powerful blasting cap that's automatically loaded onto the striker (again, by hidden interior features), just powerful enough to push the sudden expansion of gases into the cartridge, moving the rounds forward one position, enough to get pulled and thrown by the magnets. AND, you refill those blasting caps by opening and pulling back the bolt! (maybe, I'll keep thinking about the bolt)