I had a 7mm Rem mag that I tried several different powders in and it would not shoot. I had bought some Accurate powder just to blow cases out with and when I tried that, it shot .5 inch groups.
I have a 280AI that loves IMR 7828 with 140.
Rifles are funny, in that just because you want to use one bullet, it may or may not shoot it. I had Sid Goodlin build me a 260 and was going to use 123 Horn bullets, it would not shoot them for crap. Swapped bullets and it was and is a hammer.
