You should consider, when buying surplus ammunition, is that the stuff is on the market because it exceeded its shelf life. For the majority of shooters absolutely nothing bad has happened with their surplus, but every so often I have run across, either in print, or web accounts of guns that blew up with old ammunition. The stuff is cheap for a reason, and the original owner decided to get rid of this expensive stuff, precisely because it was too risky to issue to their Armies, or keep in storage.
I found this UN manual.: International Ammunition Technical Guideline, IATG 07.20, Surveillance and in-service proof.
to be an interesting read, correct with its explanation of gunpowder deterioration and the tests used to determine stabilizer content. Table one was excellent in showing how temperature reduces the lifetime of gunpowder “propellant”.
If it was not copyrighted, I would have copied and pasted.
Decide for yourselves what you want to pay for this stuff and whether you should be buying it for the long term.