With round turn-off cannon barrel, stamped with Tower proofs, engraved tutaneg action signed LONDON on one side and BUNNEY on the other, sliding trigger guard safety, slab sided butt inlaid with scrolling silver wire, complete with extremely unusual socket bayonet. There is a bayonet lug on at the muzzle of the barrel to fit this unusual bayonet. I have never seen another pistol like this. 

Bunney, Joseph (3 generations: father, son, grandson) [1730-1815]

Made brass cannon barrel boxlock flintlock pocket and coach pistols, and flintlock holster pistols with Royal Cypher; also cased flintlock duelling pistols with all accessories. Shops in London and Birmingham.

A. Merwyn Carey (1954) English, Irish and Scottish Firearms Makers, Acro Publishing Company, New York. 

Dimensions:

Bore: 54 Bore

Barrel Length: 2.4 Inches (6 cm)

Overall Length: 7.5 Inches (19 cm)