OOB premature discharge question

[tankhunter]

A few years ago I saw that we were using some old RG-69 7.62mm belted ball in our GPMG's. I spoke to the ammo techs, in passing, who said that it was old war stocks being rotated and used for training. Waste not, want not. But it goes to show that it's not the AGE that matters too much but how it's been stored

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!...............

[MGMike]

In the case of the Pakistani .303, I have not chronographed it but I don't think the cause of the extruded primers (in some instances the rectangular firing pin indent was peeled open like a sardine tin!) was elevated pressure. I did not detect any of the normally associated signs of high pressure or irregularity in the cyclic rate or cadence, felt recoil, gas regulator setting, or appearance of the extracted brass.

I believe the ruptured primers resulted from a combination of aging ("seasoning", i.e., embrittling of the copper primer cups), coupled with an incorrect alloy or improper procedures used in their manufacture.

In my view three factors determine the life and serviceability of ammunition: age, quality of manufacture and storage. Assuming a high level of care in manufacture, a long shelf life can be expected, but it is undeniable that the chemical compounds used for propellants and primers start to decompose from the day they are made, and there will eventually come a time when ammunition, no matter how well made or stored, will become unserviceable. A huge variable is the quality of manufacture. A little contamination during manufacture will kill a primer in short order. The selection of metal alloys used in cases and primer cups, and the care with which they are drawn and annealed, also greatly influence the quality and longevity of the finished product. If the bullets and primers are well sealed, and the cartridges do not come in contact with water or acidic paper, moisture is not so much a problem as temperature. Aberdeen PG has published tests demonstrating that degradation of performance from poor storage is largely attributable to excessive heat.

M

[tankhunter]

Hence on almost all British manufactured Ammo, the stenciling of 'Keep out of direct Sunlight' (Heat). This definately would affect the condition of ammo during storage & resulting deterioration.
That is THE reason why, ammunition is routinely rotated. Keeping stocks fresh & using older stuff for training purposes. ROTATION of War Reserve stocks to Training, & then War Stock Replaced with new manufacture.
If you have ever been in Any Ammo long term storage bunkers, you will have noticed they are always 'Cool' inside. I have been to a large one in Germany to get 81mm Mortar ammo for a unit shoot. There was even a shimmering shine comming off the concrete walls. Phosphorus from smoke bombs, now how the hell did that get there when ammo is SEALED VERY well in it's packaging!.........