Primer Age

There is some debate in the gun world about primer shelf life, from time to time. I was reminded by a comment here, and that's the latest reference, but I have seen the talk bandied about in much less reasonable terms previously elsewhere.

The following is true, the internet tells me so:

“Old style corrosive primers last forever if you keep the cartridges in a stable environment. Cool and dry. Modern primers can go bad in 30 years or so, but you can seal and bury the old, WWII era stuff for 100 years, no problem when your grandkids dig em up. Loose primers kept by reloaders go bad even faster than assembler-in-cartridge primers. So you MUST use loose primers within 2 years, and all factory ammo in 20 years. Older stuff will fail. Not every time, but enough.”

Now I have shot a bunch of 1970’s stuff. It’s the bargain table at my gun store. All stuff, probably from the dealer’s garage, that was made back in the days I wore knee pants and Dad wore bell-bottom jeans. I have never had a problem with a squib or dud with older ammo. Not that squibs don’t happen. I am not a big enough consumer of ammunition to even be a statistical blip on real world ammo/primer failure. But the warnings by internet authorities about 30 year old ammo going bad seems to infer if I had 40 year old ammo I’d be lucky if 1 or 2 out of a box of 50 would go off at all. And I don’t think that that is the case.

But if someone wants to give me 100,000 rounds of 1960 US Army surplus 7.62x51mm to test for duds I’d be happy to help out. Heck, I’d settle for 15,000. That’s a big enough statistical sample.

I believe the US military switched to non-corrosive in the early 50’s. So you should not run into much domestic .308 or .223 with corrosive primers.

But back to the topic what is the REAL data on primer failure due to age? The TRUE truth. The skinny. Will 2 per 100 fail on 30 year old basement-stored stuff? 10 per 100? A number less than 1 per 100? My gut says it’s this last, low, number. Brand new stuff will have .08 duds per 100, and in 30 years that number will go up to .21 per 100. Or something. Not too much for me to worry about beyond this one blog entry, doncha think? If my suspicions are actually the case.

I can see unloaded primers getting oxidized much faster than loaded ones, yes.