use both..WC-844 / WC-846 in 5.56 / 7.62, don't have my data handy (not home and don't know when at the moment) I do believe these to be WC-844 and WC-846, there is also these in WC-844T / WC-846T for loading tracers. they (wideners) are using SMP as noting it to be Surplus Military Powder, you can check here for some loads:
give them a call... they are a great bunch of people to deal with, have bought plenty components from them over the years.
those powders have used them with 55gr FMJ through 69gr in 5.56, 147 FMJ through 168gr in 7.62, with no problems, use the
loads to practice with. they both meter well through a powder measure, a little temperature sensitive. work up your loads and if lots
change do the same, some lots are hotter than others.
Surplus 844 and 846 have been around along time and I have used jugs of the stuff. Google Pat McDonald surplus powder and ask pat what the current burn rate is. It will probably be somewhere around BL-C2 or H355.