Blunderbuss

''A blunderbuss is a muzzle-loading firearm with a short, large caliber barrel, which is flared at the muzzle, and used with shot. The blunderbuss is an early form of shotgun adapted to military and defensive use.'' -Quote from Wikipedia

Game Note
Though historically available, there are currently no blunderbuss used in Pirates Online. However, they appear to be a future weapon class.