Re: WC867 Military 8lb Keg
Understand that when the government, or more properly the contractors fulfilling an ammo order, get powder from the manufacturer it is not identical or consistent with any other order from the same source. They test it and adjust their loads accordingly.
We handloaders are benefiting from an industry (SAAMI) that keeps our canister grade powders extraordinarily consistent batch to batch and year to year. Next time you look in the mirror tell yourself, "you lucky dawg..."
I have used Mil Surplus powder for years but each batch is a creature unto itself. You absolutely must do ground up load development on each batch!!!! If the supplier cannot guarantee that all the powder he is shipping you is pulled down from the very same lot of ammo (I don't think they can) then you develop (from scratch!) loads for each keg! The only work around is to buy 6- 8lb kegs and dump them in a very large container (plastic or glass) and mix it all thoroughly with a wooden spoon and hope you do a good job of it.
The Milspec # (WC 844, WC867, etc.) is a general specification. It is close but that's all. The Milspec is pretty broad. If it's pull down, how long has the ammo been stored before they sold it to you?
I use Mil Surplus powder for practice ammo and the 556 NATO stuff I load is pretty durn good. But off the shelf powder is all I ever use for Hunting and long term storage SDS loads.