Hello I have what appears to be a trade gun it's rough but very restorable was flint but has been converted. The lock is marked Tower with a crown under it W. Chance warranted . the barrel is 49"long and smaller than 20 gauge 24?. the butt and trigger guard are brass with nice engraving . the side plate is very nice with the serpintine but local experts have never seen one like it . the stock is walnut also the barrel has a fish engaved on it I'm not really looking for value but what it was and who W.Chance was and when it was made the only thing I've found is W.Chance and Son .Thank you for any info.