We were standing only 10 yards behind the trap - yeah - kinda cheating, but not if everyone does it. The double navy Arms 10's and 12's lost that day. Don was right - 1/2oz. & 40gr. of powder. Just lucky - no power and most were broken into 2 or 3 pieces only, just enough to punch my card.
Bentflint - understand the sight placement. That charge, 1/2oz and 40gr. should work well in the .40. I didn't mention in this thread (I have in others), but I did lapp in about .004" to .005" jug choke, tetween 1"and 4" back from the muzzle- that 3" section had the choke. It didn't hurt round ball shooting (snowshoe hare heads at 50 yards) which was really good, but sure evened up the pattern - better that most any .410's with 3/4oz, about par with 1/2oz which is better if choke not to tight.
If the barrel blows the patterns, empty spaces, I'll try to explain how I lapped it. pm please.