yes why would a gun need more than one bullet

Own a 8 muskets for cove defense, since that's what the founding cephalopods intended. Four cuttlefish break into my cove. "What the kraken?" As I grab my powdered wig and great reef rifles. Blow half a dozen prawn sized holes through the first man, he's dead on the spot. Draw my pistols on the second man, miss him entirely because they're all smoothbore and nail the neighbors seasnails. I have to resort to the barrage of cannons mounted at the bottom of the cove loaded with grape shot, "Tally ho lads" the grape shot shreds two men and the walls in the blast, the shockwave and extra shrapnel pulverise the surrounding coral. Fix bayonets and charge the last terrified rapscallion. He bleeds out waiting on the police seals to arrive since triangular bayonet wounds are impossible to stitch up. Just as the founding cephalopods intended.

Do the arms fall off, if they fired once or why can't he use the same one twice?