Powder question

[CHIZZ]

I shoot the Lee 340 gn out of my 45/70 and after a few drama's now have a load that I would happily go a huntin' with. With air cooled W/W and 50 gns of Varget , and with open sights, it puts five shots into two inches at fifty paces making me happy enough. The barrel slugs at .457 and the boolit drops at .459. However, when I use H322 things turn sour real fast , with six inch groups being the norm. I'd like to use H322 because Varget leaves a lot of unburnt powder behind but its not the end of the world if I had to stick with it. I was just wondering is it normal for a different powder to make so much difference with cast? I will try H4895 when it becomes available here again.

Cheers
Chizz

[AABEN]

You might tight up your crimp. That will help you some.

[Lead Fred]

My 45/70 kisses each other using Reloader 7 @ 100 yards
and Im using 400s, 405s, and 425s

[MtGun44]

10-15 gr of Unique will work very well, too.

Bill