yes, I recall when I used to work for a certain manufaturer who make .50 Cal MGs. We bought a Million rounds BACK from the M.O.D at @ 1p a round! we routinely used this for function testing at Lydd ranges. It is used so much by 'This Company' that they have thier own dedicated .50Cal range! It was old observing ammo, the type that make a brilliant flash when the head strikes a target. Well, it had been stored outside under trees for YEARS in direct sunlight, Bird crap Etc Etc, NOT ideal conditions! The magnisum in the tip had 'setteled' & it was the norm for round to expode approx 2 ft from the muzzle when firing. This resulted in a half moon shape of copper jacket shards of 'shrapnel' at the forwards end of the barrels about four feet in front on the ground. The eratic boom, bang, Phut, Bangs that were becoming the norm were unsettling at first. But after a few hundered rounds you got used to it & the violent shock waves from those exploding rounds! We were not bothered about accuracy, it was function testing the guns that we were interested in.
The cores went down the range ok but obviously were not too accurate! However, it was impressive to still observe a VERY good beaten zone at the impact area through Binos'!
Yes, storage IS important. It DOES affect how ammo perfoms. Accurately & Safely!...............