I bought 16 pounds of surplus 4831 in the sixties. While it was still available I would buy one pound cans of 4831 for less than $2 a can.
My first purchase was in two jugs provided by me at as part of the deal. Years later a friend who worked for American Can Company gave me new one quart paint cans and the powder went into cans. I have not observed any deterioration of the powder.
The best check of the quality of the remaining powder came when I ran some loads from it across the Chrony about year ago. The charges of 60-grains of Surplus 4831 with a 130-grain Remington C-L where giving 3050-3060 fps out of a fast 22-inch Savage barrel. I have not tested in my Remington barrels but they are normal 30 fps slower. I have no idea what year the 4831 was manufactured but I had my powder plus or minus forty years.
Most of the powder deterioration stories regarding WWII powder centers around 4895. It was used to load massive amounts of ammunition for the Springfield, Garand, and other rifles plus different .30 caliber machine guns. The story goes that to speed up production one or more washes in the manufacturing process were dropped in “some” lots. Later this resulted in deterioration of the powder which handloaders experienced.
First off surplus 4831 is not black powder, and is much more stable. On the job I have disposed of old mining caches of black powder and dynamite. Dynamite does rather nasty things when it ages, like leaking. The loggers were not much better leaving dynamite behind after constructing roads in the forest.
I would consider a keg of 4831 a treasure to be handled with care but a treasure. Now days I store powder in a “powder box” at floor level in my garage. I recently built a powder box for my SIL when I gifted him with some H414.
Like any other powder I would start at a minimum charge and work up. When I go for a minimum charge I consult two or three manuals looking for the minimum SAFE charge. There is a lot of loading data out there for 4831 that was developed by backyard loads that is on the hot side.
If you do not have current data I would go to the following:
http://data.hodgdon.com/main_menu.aspWatch out for old manuals as an example my of Speer Manual shows a maximum charge of 58.0 grains of 4831 for the 150-grain bullet in the 270 Winchester, and the Hornady Manual of the day shows 58.9 grains. I consider both these unsafe in my three 270 rifles. The above link shows the maximum charge as 55.7 grains.
When Hornady first came out with the 140-grain Boattail for the 270 I thought I could work up to 58 grains based on loading data for the 150-grain bullet. This speculation did not hold true and I started to get a sticky bolt before reaching 58.0 grains.
I have loaded Surplus 4831 and H4831 in four different calibers for many years.
They are not to be confused with IMR4831 which burns a little faster. The key is to build each load from bottom to top. H4831 in newly manufacture powder designed to fill the void of Surplus 4831 when the supply ran out.