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Old June 11, 2000, 11:06 PM   #1
TMC
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Obviously the word says it all but when is it corrosive? While stored or once its fired and will it hurt a frequently cleaned gun? Any info would be appreciated.
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Old June 11, 2000, 11:24 PM   #2
Stephen Ewing
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Corrosive means the priming is mercury fulminate. Store it wherever you feel like, but if you fire this stuff, be prepared to clean the weapon for three days after the fact.

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Old June 12, 2000, 12:51 AM   #3
Mike Irwin
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(deleted due to BIG factual error! )

[This message has been edited by Mike Irwin (edited June 12, 2000).]
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Old June 12, 2000, 12:51 AM   #4
Mike Irwin
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Stephen & TMC,

Sorry, but mercuric priming is an ENTIRELY different critter from corrosive priming.

Corrosive primers use a compound called potassium chlorate as part of the priming mixture.

When the primer detonates, the chemical reaction changes this compound to potassium chloride (PC). This is not a problem for your gun prior to shooting the round, only afterwards.

Like its sodium chloride (table salt) cousin, PC is hygroscopic, meaning that it draws water to itself out of the air. (Think of it in terms of black powder residue, same rusting potential.)

If the PC is not removed, it will cause rusting.

The only way to remove it is with water. PC is not soluble in oil. The old GI bore cleaner contained quite a bit of water, just for this purpose. As with a black powder gun you can use boiling water and dishwashing detergent. It doesn't really matter how you introduce the water, you just need to use quite a bit of it to make sure that you don't miss any. Even a tiny speck of PC can cause rusting problems.

Corrosive priming started to disappear from US ammo starting in the 1920s (Remington Staynless and, I think Western Klenshot), but stayed with the military through WW II and perhaps a little after in some calibers.

Commercially, corrosive priming was still used right up through the 1970s on some match ammo, including the old paper-box Eley Tenex .22 Match ammo. I know several match shooters from Camp Perry who still try to find enough of the old ammo to see them through the big matches every year.

Primers containing fulminate of mercury (which also contained PC) are problematic in another way -- on firing, the mercury is driven into the cartridge brass, which weakens it.

This wasn't really known until military powder was switched from black to smokeless, apparently the lower pressure of the BP rounds, along with the powder fouling, meant that the cases weren't badly affected. The US Army took cases fired in training and sent them back to be reloaded. When the Army switched to the smokeless powder .30-40 cartridge, they began getting a LOT of case failures on the second firing, which was eventually tracked down to the mercury in the primers.

After about 1895 mercury in primers in the military was pretty much a thing of the past, and commercial loaders in the US pretty much phased out mercuric priming before WW I. There were exceptions, though, with some match ammo made right up through the 1960s, mainly .30-06 and .300 H&H Magnum. These rounds were loaded specifically for match shooting, and the mercuric primer warning was printed on the boxes, along with a statement saying that the cases were not to be reloaded.




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Old June 12, 2000, 08:22 AM   #5
Southla1
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Excellent post Mike!! Much better than I could have written. If anyone is interested I have the dates that the US Military switched over from corrosive to non corrosive primers, it was in the early mid 50's (ie: 53 and 54). US Carbine Cal .30, was NEVER loaded with corrosive primers, reason being that the gas cylinder could not be accessed as easily as a Garand for through cleaning.

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Old June 12, 2000, 10:05 AM   #6
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Thanks, Carlyle...

Isn't it the case that SOME factories (civilian contractor) during WW II produced non-corrosive .30-06, .50 BMG and .45 ACP near the end of the war, but that the change over was not universal until the 1950s?

I've heard that several times, but have never seen it confirmed.

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Old June 12, 2000, 11:15 AM   #7
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WOW, is there any question you can't get a complete and thorough answer to!? Thanks so much. I see that some foreign manufactured ammo sold in bulk though discount suppliers is corrosive and I wanted to be sure of what I was dealing with before buying. I've been thinkng about one of thoes Jungle Carbine replicas in .303 British and found 768-rds for $129 but is 1960's Pakistani made and corrosive. Now I know. Thanks again.
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Old June 12, 2000, 11:30 AM   #8
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Hey TMC,

My personal creedo is that if it is foreign, I clean as if it is corrosive.

That goes doubly for anything coming out of the communist bloc or the middle east.
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Old June 12, 2000, 12:26 PM   #9
Jeff, CA
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On that note, where does Cavim come from? I just bought a bunch for my M-1, but if there's even a chance it's corrosive, I'd just as soon not use it at all.
 
Old June 12, 2000, 02:23 PM   #10
Coinneach
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Jeff, I believe Cavim is Israeli. I don't *think* it's corrosive, but cleaning immediately after shooting can't hurt.
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Old June 12, 2000, 02:30 PM   #11
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I'm not certain about Cavim.

As a side note, any military surplus ammo that bears the NATO acceptance stamp, the cross in the circle is, by NATO standard, non-corrosive.
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Old June 12, 2000, 02:38 PM   #12
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Hey TMC!

I just noticed that you're talking about Pakistani .303 ammo.

Along with being corrosive, it is very likely loaded with cordite powder.

While not corrosive, cordite can be very errosive because it burns with a very hot flame due to a high concentration of nitroglycerine (double based powder, like 2400).

Many vintage military .303s that were never factory updated will have severe throat erosion due to the cordite powder.

If you decide to get one of the ersat Jungle Carbines, be sure to examine the throat very carefully. The older the gun, especially WW I era, the more probable this is. I've seen Lee-Enfields with throats that are so badly burned out from use with cordite that you'd think that there should be a hole in the side of the barrel.

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Old June 12, 2000, 05:29 PM   #13
Southla1
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Mike I have heard the same thing about some of the commercial factories that made US GI ammo towards the end of the war using non corrosive primers, but like you cant confirm or find out that it was not true. I can find no written records on it.
Jeff if you can get a great price on surplus ammo that is corrosive primed the choice of course is yours, to shoot or not to shoot it, however if it were me, I would elect to shoot it. I have run through many many rounds of it and have never had a problem even in the high humidity climate here in South Louisiana. I use Tide laundry powder and boiling hot water, works like a charm!


Carlyle Hebert

[This message has been edited by Southla1 (edited June 12, 2000).]

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Old June 12, 2000, 09:57 PM   #14
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I almost wish I were beside myself. I have an overwhelming urge to simultaneously stand both corrected and in awe.

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Old June 13, 2000, 12:40 AM   #15
Mike Irwin
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No need, Stephen!

We've all been there and most of us still are there in some, or many, arenas.

It's truly the poor person who doesn't learn something new every day of his or her life.

Why, just today I learned that my boss isn't only a pain in the butt, he's also a dangerously devious individual. I'll be leaving his employ very soon, I think.
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Old June 13, 2000, 10:48 PM   #16
alan
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TMC:

Some good posts already, but simply put, clorate primers were/are corrosive, will rust barrels, except perhaps for stainless steel barrels, depending on exactly what alloy is used. clorate (corrosive) primers aren't used in contremporary ammunition and U.S. military ammunition later than mid 1950's, check NRA handbook.

Essentially, mercuric primers ruined cases, didn't bother barrels. Haven't been used in many years, with few if any exceptions.
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Old June 14, 2000, 08:55 PM   #17
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CAVIM ammo is from Venzuela and all current production stuff from them is non-corrosive. It also shoots pretty good, too.

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