Dear Mohammed,

Thank you for contacting Mearto with your appraisal inquiry. My sincere apologies for the delay with the appraisal.

The presented object appears to be a Robert Adams double-barrel side by side shotgun. The barrel is stamped and as percussion locks.
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 400 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