Powder for 7mm RM? That's easy.
Anything around RL 22 burn speed will work reliably.
Unfortunately RL 22 requires different loadings for Colorado summer ( 80*F)
and winter ( 0*F). Just a little temperature sensitive.
A couple of my current favorites:
Win 780 Supreme is the all time favorite. When you can get it.
71+ gr. of Ramshot Magnum will provide outstanding velocity,
68 gr. Accurate MagPro works well too. Works so well that I just picked
up 2 more pounds of it. These like F 210 and WLR primers.
I have also noticed how hard it is to find powder these days.
It has occurred to me that I might want to hold on to a 7mm Remmy mag.
If only because it's so easy to feed.