CAREFUL: Be aware that IMR 3031 was pretty popular back in the 1970’s & 1980’s for Nitro Express loads as it roughly duplicates the burn rate of Cordite. Elmer Keith, Ray Marriage, and other double rifle enthusiasts back in that day used it.
That said, it fell out of favor because it “can” be pretty erratic in Nitro Express size cartridges and some few double rifles were wrecked……there are better more modern powders that are not as problematic.
- yes, I am aware that Ken Owen and JJ Perodeau do recommend using it in Full Nitro Express duplicating loads.

Yours looks to be a very early (circa 1870 ish) BP Express so use care.

Just my 2¢ worth.

- Mike