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Is there any kind of consensus on how long the sinoxide primers of GP11 last? It seems there are reports of it going dud much sooner than other surplus or even regular civilian commercial ammo. Was it just stored poorly, or is the particular non-corrosive primer compound of sinoxide not as shelf stable?
 

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Let's see, I am shooting some old berdans, Swedish, marked 1953 and all go off, one in one-hundred may let off a light ignition. These are just primers for reloading. So 67 years so far. Depends much on how they were stored.
 

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I think your question is on GP11.

here is what I have found:

1978 to 1992, all Swiss surplus sourced from Switzerland: No failures or hangfires, very accurate. Several thousand rounds expended.

May 1973 Altdorf, sourced out of Canada, one brick shot by chap I know, stored in a persons closet for the last 20 plus years. Shot well, or so I was told. I assume it came out of the Ontario rifle club over 20 years ago.

1959 GP11, sourced out of Egypt, apparently part of the old overseas club, exact storage history unknown. When imported unknow but likely 1980s. Hangfires and dead rounds.

DAG 11th week of 1959, DM41 7.62 NATO ammunition, purchased in or around 1986, stored in a house since, last fired in 2019: no hangfires in 20 rounds. (German 7.62 NATO from 1959 used same sinoxide primers). This lot was fired in a British Envoy for accuracy tests, show very well @ 100 yards, no chronograph test results.

So a reasonable interpretation is Swiss GP11 stored correctly should give at least 50 years of service at a minimum. If stored in ambient northeast conditions 60 years is likely possible. But a prudent man might consider utilizing the ammunition if match shooting sometime around age 50 to 55, as once it goes bad it is pretty much a display item. So 1979 should be expended by 2029 to 2034, 1992 (last lots known to be imported into USA) by around 2042 to 2047
 

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Discussion Starter #4
Thanks for that information! The duds I've read about could have been those lots from Egypt and had me worried that my ammo might start to go bad soon.

I bought 20 cases of GP11 back when they were $240 and managed to get 5 cases of '92, with the rest split between '79 and '84. I'm not a competitive shooter, just take the ol' Swiss Miss out for a brick or two on some steel plates. At this rate it'll be at least 10-15 years before I've burned through the '79 lots. Luckily I live up north and all the ammo is stored in a climate controlled basement (65 degrees) in ammo cans with desiccant. No idea how the Swiss store their ammo, but it's probably in an ideal storage now.
 

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The service life of any ammunition --not just Swiss-- depends on three factors.

1) The materials and workmanship employed in its manufacture, which may vary from lot to lot. The slightest lapse in quality control --particularly in primers (the manufacture of which is akin to sorcery)--will be discovered sooner or later.
2) Its absolute age. Ammo is not like bourbon, it does not improve with age. The chemicals in primers and propellant begin to degrade from the day they are made.
3) The conditions of its storage, heat being the principal killer (aggravated by imperfect sealing of bullets or primers, coupled with wide temperature extremes).

It is futile to draw broad conclusions based on anecdotal experience with a few samples from different sources.

M
 

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I’m not up on European trade names, but I think Sinoxid primers are just a standard lead styphnate/barium nitrate composition, so they should last many, many decades.

I suspect a lot of times aged ammo not firing is due to the degradation products of the smokeless powder destroying the primer, rather than the primer itself degrading. Nitrocellulose inevitably breaks down into various NOXes and an additional ingredient prevents that process from going autocatalytic (usually a secondary amine, like diphenylamine). Once that’s gone, breakdown is fast. Since it’s heat that accelerates this unwanted reaction, and since GP11 was probably never subjected to poor storage conditions before it got to us, any lot we got our hands on here in the States will probably outlast us.
 

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You have to distinguish between Berdan and Boxer "Sinoxid" primers. The Berdan primer is sealed while the Boxer primer has its contents exposed under the anvil. Most - all? - European military ammo used, and still uses - Berdan primers. Stored under decent conditions of low humidity and moderate temperature, Berdan primed GP11 made after 1950 can last a very long time and remain fully serviceable. (Prior to 1950-1951 GP11 had mercuric primers, which although noncorrosive also had a short storage life.)
 

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A friend found his grandfather's 1911 from WW1. Gun was loaded and two extra clips in the holster in the old mans closet with his uniform. He had put it away when he got home. Without even cleaning the gun, the dummy shot it all up, but he saved the brass. All dated 1917. So ammo will last a long time and magazine springs do work after being compressed for 80 years.
 

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A friend found his grandfather's 1911 from WW1. Gun was loaded and two extra clips in the holster in the old mans closet with his uniform. He had put it away when he got home. Without even cleaning the gun, the dummy shot it all up, but he saved the brass. All dated 1917. So ammo will last a long time and magazine springs do work after being compressed for 80 years.
Dummy also probably neglected to clean grandad's 1911 after shooting the GI-issue corrosive ammo.
Corrosive primer compound is very stable and has a very long storage life - if correctly stored - and is why most European military ammo was using corrosive primers even when non-corrosive primers were available. Corrosive ammo could be stored for stockpile for ages. The exceptions were Switzerland, with mercuric primers, Sweden and Finland.
 
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