Thanks, Jones. I don't handload, but I like your thinking! Estate has a 20-gage 1-0unce load moving at 1165 fps. Plugging those numbers into the calculator Dr. Hause linked to yield recoil energy of 21.6 fp. The 7/8-oz 20 gauge NSI "target" loads sold by my gun club have MV of 1275 fps and an estimated recoil energy of 20.5 fp. Now that is a load I've shot 50 rounds in one go. I may pick up a box ot two of the Estate or other relatively low-velocity 1-ouncers just to see how they feel and pattern in the Darne.
Bill