A musket is also a falconry term for a male sparrowhawk, as I'm sure Chris will confirm.
Muskets, as firearms, were basically obsolete by the middle of the C19th but were still in use during the American Civil War, mainly by the South, but the dominant infantry weapon used by both sides was the muzzle loading percussion rifle.
FWIW, repeating firearms using self contained metallic cartridges also appeared during the war. These included the 16 shot Henry, which some Southern troops reportedly called 'That damned Yankee rifle that you load on Sunday and shoot all week'.