I think you need to find a knowledgeable dealer(or someone on this board) who is a Francotte expert to appraise your gun. Going by the pictures it looks like a 140 series shown in the repro catalog I have. I think maybe the engraving will determine if it is a "best" gun in the 140 series, but only a really knowledgeable person can give you a true appraisal(and maybe only if you are willing to pay a fee.) I think it might be worthwhile to get a professional appraisal. Maybe you could negotiate a fee in advance. There is a similar Francotte being offered for sale at $30,000. What your gun might be worth is an open question. If it were mine, I would want to know.