If it was me I would keep rolling with the Winchester Double X #5 in 3.5 inch if that worked for you last year, especially knowing that POA and POI were on point with your bead sight. If it's not broke, I wouldn't worry about trying to fix it. That shell is a good killing shell anyway; it hits hard in my experience and seems to crumple birds up. I don't get too caught up in the #'s game like most people do, I'm trying to kill Spring Gobblers not win a still shoot competition. There is a big difference between hunting shots and still target shooting. If that 70 was pretty even at 40 yards, I would definitely hunt and kill birds with that. I don't put much into bad batch or bad lot numbers, most of that is hype. You could try another box but I would bet money they will shoot like the box you already have. Knowing that, it's definitely the shells not the gun being off. I saw the same thing with Longbeards frequently. In my gun they would pull about 7 or 8 inches to the right while every other lead shell was dead on with the bead. I prefer hunting with a bead sight for turkeys. Rifle sights are better for rifles, shotguns I want just a bead.