Swiss emailed back. I find it hard to believe that 3 different brands of guns hate swiss powder? Especially when they all shoot different projectiles. There's no way I would be able to hunt big game with the charges listed below.
"Good Morning,
I shoot that same lot with a .45 caliber and I don’t have any issues with grouping. It just could be that your rifle doesn’t like that powder. I do have a rifle that doesn’t like Swiss powder at all. I have one, that will only shoot Swiss and I have one that will shoot anything I put down the barrel. Rifles are just like people I have figured out.
When shooting this Swiss with my .45 caliber, at 25 yds I am shooting about 20 grains, 50 yds, it’s 30 grains, and 100 it’s 40 grains. My grouping off a bench is about 1.2-1.5”, at 100 yds. Off hand, I get about a 3” group (I am not very steady) But I can shoot pretty tight groups closer in off-hand. My last time out I shot a group off hand under .75” with the same lot of powder that you are having issues with."