This 17th century blunderbuss would have been used primarily mounted as a swivel gun on a naval vessel given its size and would have been a very effective weapon against boarding operations or for weakening the opponents crew before mounting your own. Blunderbusses were in use in varying forms from the early 17th century into the 19th century. Minor details changed over time and there are great variances in bore sizes depending on their intended use, but many follow the basic form. Thus, the swivel mounted blunderbusses used by Lewis and Clark's Corps of Discovery at the beginning of the 19th century were essentially the weapons as this example but had the more modern flintlock mechanism. This example has a relatively straight bore with a slight flare at the muzzle which is 2 inches across the inside edges. The stepped muzzle is very similar to those seen on English swivel guns used during the Seven Years War (French & Indian War) and American Revolution. The only markings are three London proofmarks on the left at the breech and "W D F" stamped on the right side of the butt. The stock is smooth and has a bare butt and no trigger plate. The trigger instead suspends from a pin above the lock. The dog/English lock was popular prior to the adoption of the true/French flintlock mechanism. It fell out of favor with the British by the beginning of the 18th century but was previously widely used. The catch or "dog" at the back of the lock secures the hammer and prevents accidental discharges while loading or carrying the weapon. The early English locks which were an improvement on the miquelet and snaphance locks, but were evidently known for "going off half-cock." The catch prevents this from happening and was even used on some English firearms nearly a century after the true flintlock mechanism was invented around 1630. When the shooter pulls the cock back to full-cock, the catch is automatically released and the weapon can be fired.