It's World War II powder for 20mm cannons. It was either retrieved from broken-down 20mm rounds, or powder that hadn't been loaded yet by the end of the war. Hodgdon bought tons of it and sold it as H4831 until they ran out in the early 1970's. So it's around 70 years old.
John: Let me know if you can spare a few pounds. That Mil-Surp 4831 is all we ran in our .270's up until a couple of years ago when we ran out. It has no equal in the .270 with 130 pills.
