Dear Samantha,

Thank you for your help and patience. My sincere apologies for the delay with the apprisal.

The presented object appears to be a percussion lock boot or ship pistol made in the first half of the 19th century. The lockplate is marked by an unknown gunsmith with the name "M. Duguid" and sadly no proof stamps ate visible to localize this pistol. Duguid could be a British or French name. Pistols with brass barrels were usually used on ships because of the corrosion through the salt water.
Comparable objects were recently offered and sold on the international auction market. 
This piece is in good condition and there is no serious damage visible in the images provided.
A fair market estimation would be between 150 to 300 USD.
This estimate is based on actual recent past recorded auction sales of comparable items. Retail "asking prices" can be higher and may vary.

With kind regards,

George