Stan, those are better looking POI patterns. Interesting what a small change will do to POI and convergences. The pressures on those shells are about as high as I am happy to go at 13K to 13.5K. 13.5 is the MAP for 3" .410 loads according to SAAMI. I know you are using a modern gun which should be fully capable of handling them. I'd contact Hodgdon and Alliant powder to see what they have for loading data. I have had great loads using 300-MP and 296 but pressure is only half your problem. You might need the full 13.5 and a similar burning rate to keep your POI where you want it. So it will be reload and retest until you get the results you want.
I have seen a few people who reload, have this dumb idea that slightly more powder than called for will not make much difference. In the .410 a increase of .5 grains may cause the pressure to go up 500-600 plus psi which does not sound like much until you get to those 13.5K loads, Worse are the idiots who go a full grain over recommended loads. Pressure is not a linear thing in reloading, it would be so much easier if it were.
One local Skeet club shooter was having primers flattened and the primer puncture and he could not figure out why on his .410 reloads. I cut one of his reloads apart and found he was loading 1.7 grains over the recommended load which was 12.5K. In 2 1/2" .410 MAP is only 12.5 and that extra 1.7 grains had to be pushing his pressure well over that to almost proof load levels. You can't fix stupid but you can refuse to shoot on his squad.
