That's the problem with surplus powder. It comes and goes and sometimes has larger lot-to-lot variations than commercial canister powder. It is cheap though.
I would work up a load using canister powder that you can buy easily so you have a backup to WC844. The logical choice would be the very similar H-335 that can be found locally or online.
Widener's will notify you when it is back in stock if you click on that option.
However you probably should re-work up your load again because it would be a different lot and those wider swings in burn rate can come into play.