Dear Judy,

Thank you for contacting Mearto with your appraisal inquiry.

The presented object appears to be a percussion pistol with one barrel. The barrel hallmark identifies this gun as a product of the city Liege in Belgium. Liege was famous for its gunsmiths who exported arms to Europe and America. It was probably made in the middle of the 19th century.
This piece is sadly in bad condition.
An estimation would be between 40 to 80 USD.
This estimation is based on actual recent past recorded auction sales of comparables. Retail "asking prices" can be higher and vary.

With kind regards,
Georg