In the 1990's a friend of mine bought an Austro-Hungarian Mauser in 8X54? if I recall. Whatever, it was an obsolete cartridge so he could buy it without an FFL. He also bought some ammo that was headstamped 1905 and it performed perfectly.
Also in the 90's I bought a Holland and Holland double rifle in the .303 Mk VII caliber. The rifle was regulated with the 220 gr. bullet and the only ammo I could find was from Don Shrum. As I recall it was certainly pre WWII, cordite, and corrosive primed. It fired more like a percussion muzzleloader with a "clap-boom" report. However, it reliably fired and was quite accurate.
I had always heard the Hercules Unique powder was incredibly long lived. At the NRA show in New Orleans I believe in the 80's I asked the Hercules people about that. They said it was true. They had a powder from the first batch they made and would periodically test it and it performed perfectly.
Smokeless powder is a chemical compound while black is a physical compound. Chemical compounds can degrade yet ammo and powder carefully stored can easily last a century or more. Black will last forever so long as it's kept cool and mainly dry.
