FWIW, from the Blue Book of Gun Values:

http://www.cheaperthandirt.com/EveryGun/GunMfgCategoryDetail.aspx?id=737

"Original A. Francotte SxS shotguns must have the "Francotte Choke Bore" marking on the water table. Be wary of fake barrel and frame markings, as some guns have recently surfaced that are not Francotte but have the Francotte name."

Regarding the gun in question, the two 'crown over AF' marks, along w/ the large 'F' in front of the flats, just look 'wrong' to me...JMHO.

Always looking for small bore Francotte SxS shotguns.