This gun was most likely originally mounted as a swivel gun on a ship or boat in the late 17th century or early 18th century. These guns were useful in close in ship to ship battles for firing upon the enemy's boarding parties or softening up their crew before mounting your own boarding operations. The bore is relatively straight and measures approximately 2 inches at the muzzle which certainly brings it closer to a small cannon than a small arm. The left side of the barrel near the breech has London proofmarks flanking a "crown/IB" maker's mark. The lock has an unclear maker's mark and flat profile. The stock has a crowned "R" on the right side of the butt,