A friend of mine owned twelve 8 Bore double rifles and four 4 Bore double rifles, two of the 4 Bore double rifles were Rodda's fully engraved and made for the Nizam of Hyderabad. They weighed 22 pounds each and were MUCH more massive than the above double rifle. I agree with TH44 and Huvius that it is an 8 Bore. Probably weighs 15 to 17 pounds.