Re: WC872 and 7mm SAUM
Too slow. You will get the best performance from powders like H1000, Retumbo, IMR 7828 with the heavy bullets.
For the mid to light bullets, H4831SC, Re22, even H4350 would be my first choices.
Look up the Hodgdon website for more load info. That gives you a base to cross reference with other powder types.
The WC872/H870 really work well in the 7 Rem mag and STW and 162gr bullets. The smaller case just doesn't have enough room to use this slow of a powder. Especially, in such a short barrel.
If looking at surplus powders, the burn rate around H450 would be appropriate. I think the suplus number is WC 852 or something like that. Only problem is that some of these powders do string because they don't burn consistently.