[JamesKelly]

This plain pistol is of large caliber, 20mm, with a 230mm long barrel. The barrel is 30.3mm dia some 9-10mm ahead of the breech. This is identical to a British Light Dragoon pistol, marked Williams, in my Accumulation. By contrast, an India pattern Brown Bess of mine measures 33.9mm dia at similar location. By these measurements I assume the pistol barrel was intended to be 20mm caliber, and not a cut-down musket barrel. No visible proof marks. The lock and breech end of the barrel have some black paint, which might be consistent with sea service except it looks to have been applied after some corrosion and pitting had already taken place. The large bore permits a standard musket ball to be used.
I will probably go through life assuming that this is an English Sea Service pistol unless you gentlemen have other ideas.