Hello Lou,
I strongly suggest you treat yourself to a copy of "The Road to Yesterday" by the late Dick Baldwin. Dick was the managing director of the Trapshooting Hall of Fame. The book is a treasure chest of stories about old trap shooters and their guns. Tons of photos.
Here is a 4E set up for trap. Vent rib does not show but it is there.


or if you would like a bit of an upgrade--



Last edited by Walter C. Snyder; 01/12/10 10:32 PM.
Walter c. Snyder