I looked at a unsigned Shroyer about four years ago at the KRA show. It was in great rifle in good shape, well carved, no box as I recall and I am not sure if it was rifled. It was selling at what I thought was a reasonalbe price so I looked really hard at it. I think there are more bogas signatures out there than some would care to admit. It is fairly easy for a signature to be added to a rifle. It is very hard to duplicate a building process. Each builder had their own way of doing things and tools to do them. If you look at the building technique and methods, tool marks, carving style, metal finish, it is fairly easy to attribute an unsigned rifle if you have examples to go by. With Schroyer having many rifles out there and well published it should be fairly easy to attribute the rifle or smooth bore. I was fairy comforatble that the gun I was looking at was a Schroyer but unfortunately I was unable to get the gun. One of those things that I still kick myself in the backside over.
Collectors like a signature and I am no different, but a well made gun that has those tell tale signs of a signed gun is also good in my book. As far as how it affects the price, this gun that I looked at was probably about $35,000 + cheaper than a signed Schroyer at that same show. Now if the gun had a patch box I am sure it would have been more but still well below the signed rifle.