Stan, I hate to say this but you are searching for something that is probably going to fly off the vendor's table as soon as the show opens. Chances of finding it before someone else is not good. You will be competing with the other exhibitors as well as Joe Public. Hammer pigeon guns have always been rare, are getting rarer and are one of the few specifications that are easy to sell nowadays.
If you don't want to waste time visiting shows, contact ALL the big dealers and make it clear you are VERY interested in the specific gun you require and have a budget of X. Be prepared to buy the first gun they offer you, they won't try again! Sadly you are going to be competing with people with very deep pockets who will buy whatever the dealer offers and sell it on if it's not what they want.
Most of the big boys will be able to place a gun such as you seek without ever laying hands on it, it will go pretty much direct from their supplier to the end user.
I work a little differently, I nearly always exhibit everything I restore at shows I attend but my business model is different as I have to bring everything in from the UK.
As said above, the Beinfeld show has nothing to do with black guns and cammo but it also has quite a few less big antique gun dealers than itdid in previous years. Some have ceased to exist and some have just stopped coming but the likes of Steve Barnett, Kirby Hoyt and, dare I say it, myself are still flying in to show our wares.
I wish you luck in your search.
