19th Century Prototype Revolver

If it's a prototype, it would NOT be similar to other known examples. What the seller needs to do is track down how and where he found it and where they got it from. Provenance is everything.

He should have word with the colt factory and museum and let them check it out. I'm a bit dubious about all these so called experts he knows lots of changes we're made on prototypes he's using a modern picture for comparison