Mode 21, Your barrels missing anything?
Here's that A-1 Special trap that sold through Cowan's. It has Krupp barrels.

I think Tom Archer explained it to me best, approx. To realize higher prices, you are really looking for a collector interested in the Syracuse guns. They just don't have that big of a following.
Some of the highest grade Syracuse guns are so stylized, I don't enjoy them. Too much ebony, and the grip shape creeps me out.
The one in the NRA collection is magnificent though.
http://www.nramuseum.com/the-museum/the-galleries/freedom%27s-doorway/case-82-right-display/syracuse-arms-side-by-side-shotgun.aspx