Primer shelf life?
- Thread starter Shadow9mm
- Start date
mikejonestkd
New member
Primers last decades as long as they are kept cool and dry
No doubt, Unclenick will chime in and complete the discussion 
I have a personal anecdote:
In 2013, I was snooping around at my Father's house. In the linen closet - where I used to stash my powder and primers, I found CCI's 300, 350, 500, & 550's. I had totally forgotten about then. I purchased them no later than 1987; probably '86. Anyway, I loaded them up and they all ignited flawlessly. Granted, their storage was in near-ideal conditions: dark, dry, temps in 60's-70's the entire time.
P.S.: Also found at the time was a used # of each 231 and 296. They performed flawlessly as well.
I have a personal anecdote:
In 2013, I was snooping around at my Father's house. In the linen closet - where I used to stash my powder and primers, I found CCI's 300, 350, 500, & 550's. I had totally forgotten about then. I purchased them no later than 1987; probably '86. Anyway, I loaded them up and they all ignited flawlessly. Granted, their storage was in near-ideal conditions: dark, dry, temps in 60's-70's the entire time.
P.S.: Also found at the time was a used # of each 231 and 296. They performed flawlessly as well.
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The old potassium chlorate primers would last indefinitely like black powder does. The mercuric primers would deteriorate, sometimes in just a few years. It is one reason the military used chlorate when mercuric primers were still the only non-corrosive primers available. Lead styphnate primers have been adopted by the military (your first clue that they are at least very reliable and I haven't encountered a military stockpile time limit for them), and I have never heard of properly stored ones breaking down, but then, I don't hear everything. The new Federal catalyst primers, however, use nitrocelluose, so they will have a stabilizer, I assume, and will eventually age out.
reynolds357
New member
Depends on the shelf.
I have some large rifle Winchester primers that are at least 45 years old. I think they actually say Olin. Shoot just like new ones.
Some years back there was a run on primers due to a scare rumor about "new" primers being made to expire after a set length of time. Supposedly some new "secret" govt requirement they would go dead after a year/5 years / pick a time...
It was BS then, its BS now.
I don't know about the new Federal primers Uncle Nick mentioned, he's probably right, he usually is...
The point is that there is no way to make a chemical compound that will stop working after a certain specified time. The "expiration date" on ALL commercial chemical products is the date the manufacturer chooses after which they will no longer support the product. IT MAY go bad after that date, or it may last much longer and still be usable, but the maker won't guarantee it after that date.
There's no way to make a primer that will go bad after say 5 years, that won't have a percentage of the batch go bad right away and a percentage of them stay good longer than the target date. That's just the nature of things.
It was BS then, its BS now.
I don't know about the new Federal primers Uncle Nick mentioned, he's probably right, he usually is...
The point is that there is no way to make a chemical compound that will stop working after a certain specified time. The "expiration date" on ALL commercial chemical products is the date the manufacturer chooses after which they will no longer support the product. IT MAY go bad after that date, or it may last much longer and still be usable, but the maker won't guarantee it after that date.
There's no way to make a primer that will go bad after say 5 years, that won't have a percentage of the batch go bad right away and a percentage of them stay good longer than the target date. That's just the nature of things.
Airborne Falcon
New member
Modern primers are nearly ageless if properly stored. That's the bottom line.
And it doesn't have-to-be between 50°-70° either ... -0 - 88° F is not gonna hurt'em. Now, when it gets above 90° there is exponential degradation that does occur but it's not drastic until it's over 100° and even then it takes awhile.
What does more damage to primers is large swings in temp and humidity where a breathing type action takes place usually inside the storage container. A sucking type attempt at equilibrium inside ammo cans that are not properly sealed. Cans expand in the day and shrink at night during certain times of the year.
Mind you, there is some debate or argument over whether or not primers last longer in storage or in loaded shell casings. General consensus is that they do, in fact, last longer once seated and loaded in brass cases.
And it doesn't have-to-be between 50°-70° either ... -0 - 88° F is not gonna hurt'em. Now, when it gets above 90° there is exponential degradation that does occur but it's not drastic until it's over 100° and even then it takes awhile.
What does more damage to primers is large swings in temp and humidity where a breathing type action takes place usually inside the storage container. A sucking type attempt at equilibrium inside ammo cans that are not properly sealed. Cans expand in the day and shrink at night during certain times of the year.
Mind you, there is some debate or argument over whether or not primers last longer in storage or in loaded shell casings. General consensus is that they do, in fact, last longer once seated and loaded in brass cases.
Perhaps, based on the fact than when loaded as ammunition they are sealed off from the outside air.
On the other hand, they are not sealed off, from, and in fact are in constant contact with the air in the case, so if the powder begins offgassing due to chemical degradation, the primer is trapped being exposed to it.
No free lunch....
Board member Slamfire posted information on Naval Ordnance testing of M80 7.62 ammo to study powder deterioration. They pulled down half the sample they were aging in, IIRC, 140F for a good number of months, so they could age primed cases without powder to isolate primer changes from powder changes. The powder deterioration at the end raised pressure by about 1.5X, due to deterrent being broken down faster than the nitrocelluose and nitroglycerin in the powder, so it made the powder faster burning. The primed cases were charged with powder that hadn't been aged and bullets repeated and it behaved like the unaged sample they didn't hear in the oven. So, the heating had no effect on the primers.