Mark;
I have a 10ga E grade SN 10515. It has the side pivot opener & is I suspect what you describe as clover leaf, though there are variations I beleive on the shape of a side pivot lever. This gun also has the bushed firing pins, the spanner type ball screw & is a cocking rod gun. The thumb screw & pivot opener guns had a vertical bolt which entered the rib extension slot from the rear. The center pivot top levers had the bolt as an extension of the lever which entered the slot from the side. These early guns had the extractor cam in the forend & the Ball Screw had a concave end for the cam to fit in, thus the spanner holes. The extractor cam was removed from the forend about the time of the small single cocking hook guns. The two hook guns I have seen have all had the forend cam & the spanner ball screw. As Topgun has said though this was a period of transition & never be surprised if you find one which doesn't fit the "General" descriptions. My E incidently has only scroll engraving, no dogs or game. What type does yours have? It also has several "Compensation" features not present on later guns.
