Check this picture. The action is almost like a Frank Wesson tip up type rifle, but the receiver is way different. I'm assuming the front trigger opens the action, and the rear fires it. Anyone seen one of these? For sale on Armslist, and not far from me.
http://www.armslist.com/posts/7798698/nova-antiques-for-sale--old-single-shot-12gauge-
http://www.armslist.com/posts/7798698/nova-antiques-for-sale--old-single-shot-12gauge-