Larry, sorry for my post which was not clear. I believe the Betts gun is from the 1920s, but the other two are --------Greener 16 bore from 1900 and the Cashmore from somewhere around 1905-10. The Greener has 16 over C in a diamond with an extra mark on the barrel flat of "2 3/4 Case". If I am reading Englehardt correctly from your post, he would say that this gun should be marked with a 16 over LC in a diamond, which it is not. Same thought on the Cashmore ca. 1905. It is marked with a 12 over C and with " 3 in. cases " on the lower rib in front of the barrel flat. Both of these guns seem to be contradictions of Englehardt, whose explanation of the C and LC mark differs from Wirnsberger. It seems Wirnsberger is consistent with the guns at hand. By the way, no evidence any reproof on either gun.
