Well, that’s interesting. Still, the powder would be undergoing chemical reaction even at a low rate. How many didn’t go off, or were squid rounds? Anyway that’s off-topic!
Proper cleaning negates the primer issue. I have 45 acp and 9mm from just about every era including modern manufacture. I don’t own modern round hand weapons like 10mm or 40cal, sources too limited. I reload, 357 mag and 44 mag and all my 12 gauge shotgun and my centerfire rifle rounds, for 30-06 and 270. I have more 22 LR rimfire than I have space. All told I do not own a gun without at least 1000 rounds. Most are more like 2000 and the 22 LR is like 5000+.
Ammo will last for many decades in stored correctly.