You haven't got one of these .... A very unusual double pinfire shotgun circa 1860 , almost certainly Belgian and a "one off" , or prototype . It has a rotating action operated by unscrewing a knob on the underside of the action and tilting the barrels sideways for loading . I suspect this is the only one of these in existance , possibly having been made by a good gunsmith as a commission by the "inventor" . Nice twist barrels and good quality locks working well with very strong springs etc. Nicely figured walnut stock . It has a brass plaque on the stock showing it as being part of a private collection , possibly that of the person who had it made .A very interesting object and I think great value at £495 . Can be viewed / collected SW London , or posted UK for £20 .