An ignition adapter apparatus for use in rapidly charging a muzzleloader while preventing gas leakage. The ignition adapter apparatus preferably defines a primer carrier device shaped such that the outer surface thereof conforms to a standard ammunition cartridge. The ignition adapter apparatus further includes breech plug adapted to fit into the breech end of a muzzle loader. The primer carrier is preferably constructed of a metal that is softer than the breech plug. When the primer carrier device is pressed into the breech plug, the primer carrier deforms such that a seal is formed between the primer carrier device and the breech plug. Using such ignition adapter apparatus in a muzzleloader reduces or eliminates no blow-by resulting in a more powerful shot and a cleaner firing mechanism. The primer carrier device may be magazine fed for rapid re-priming.