tarawa, I had the same experience and found out the same info the same way...after a lot of back and forth with EAA.

My problem was with a couple combo's that I wanted to center a buckshot pattern at 25 yards with the same sight hold I used for the rifle barrels at 100.

Long story short, I had 4 of the combo's. One was perfect but it was busted up in an accident. Of the others, one was OK but had the grossest stock on planet earth and I sold it. The other two were hopeless, but hopeless because of windage problems not elevation. I do believe a guy could monkey with elevation after a fashion, as you are doing here. But when the rear sight is literally hanging off the starboard side of the gun with every load imagineable, not sure what to do.

I think you are on the trail to getting the things to work.

{PS: Totally off topic, but your handle reminds me... My Dad was a Navy Hospital Corpsman in WW2 and was assigned to work with psychological cases. He told me of one Marine Major who was a very serious case, repeating "My boys, my boys, my boys..." over and over again. He had something to do with planning the Tarawa invasion and completely broke down after it, devastated by the lives lost during that mess. He became suicidal eventually and without warning one day charged down the hall of the ward and dove head first into a cast iron radiator at the end of the hall. The act did not kill him but broke or somehow damaged his neck severely and he was transferred to a medical ward permanently. Very sad. Anyhow, I suspect you may have some involvement with that battle, be a student of it, or have a relative who was involved? If so, here is the story of another casualty...}