I've looked at the inside of the call and of all of the Gibson's I've seen I've never seen one with mortise marks on the bottom of the sound chamber . In addition most of the Gibson's have very sharp angles on the sides of the sound chamber .
Yes of course. This call was looked at by a few well known Gibson collectors and also had a solid chain of custody letter. Gibson did a lot of different things with his calls. I think he may have been the first to use cocobolo as well.
"Instruments of Mass Destruction"