Stan;
Happy to hear that worked out for you. This will make that little .410 a lot more useful for you. Makes me a bit confident I was right in my diagnosis way back early in the thread that the loads simply were not torquing the gun enough to offset their built in convergence. I am like you though I won't have thought the change from 11/16 ounce to 3/4 ounce would have made that much difference. Must have been getting virtually no side "Twist" with the 11/16 (or 1/2 ounce) load & the extra 1/16 oz of shot plus the lower muzzle velocity put it just over the edge & allowed the needed sidewise movement to the barrels. For this thought we definitely have to give Jonsey Full credit, I would have though it would have taken far more than you could have stuffed into a .410 hull to make that much difference.
