They call these things muzzleloaders, but although the powder and bullet have to be put in from the front end, the primer is contained in a "cartridge case" that is inserted in the breech, with a regular bolt which locks into place behind it to contain the elevated pressures produced by the smokeless powder charge. Hence, they are actually "breech-muzzleloaders", a hybrid sort of arrangement!! No wonder some states are considering banning these during muzzleloader seasons.

Larry