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sigman2 05-14-2010 01:40 AM

How To Determine If Ammo Is Corrosive Primed
How to Determine If Ammo Is Corrosive Primed

Here is the method I use:

1. Pull the bullet and dump the powder from the suspect round.

2. Pull the bullet and dump the powder from a known non-corrosive round. If you are a reloader prime a resized case with a non-corrosive primer.

3. Take a piece of steel (don’t use stainless) at least 3” wide and 6” long and sand the surface until it is clean and bright.

4. Mark the upper end “control” and the lower end “suspect”.

5. Tape an empty toilet paper roll to the steel just below the word “control”. The roll will keep the primer flash residue isolated.

6. Chamber the non-corrosive primed case in your rifle. Place the muzzle in the tube about an inch or so. Fire the cartridge. Remove the tube and discard. There will be some blackish residue on the steel.

7. Tape another toilet paper roll to the steel just above the word “suspect”.

8. Repeat step 6 with the suspect case.

9. Place steel in a protected place outside and let it sit overnight, longer if you are in a low humidity area. Another option is to place the steel in the bathroom when you take a hot shower.

Use several patches soaked in hot, soapy water. Run two patches soaked in plain hot water through the bore followed by two or three dry patches. Finally run a well oiled patch through the bore. Personally, I prefer to use WWII GI bore cleaner. It was formulated specifically for corrosive primed ammo. Just clean and oil as you would normally.

11. If the suspect ammo is corrosive primed the “suspect” area will show signs of rust after sitting outside for a night or two. There will be a marked difference between the “control” and “suspect” areas.

12. Now you will be certain as to whether or not you ammo is corrosive primed.


Fire the non-corrosive case first so you don’t contaminate the bore with salts and compromise the test results.

Cleanup will be easier and faster if you use a bolt action rifle. For testing I have a junker Japanese Type 99 barreled action that I reamed out to .30/06. This can be used with any caliber with a rim diameter the same or similar to the .30/06 by placing the rim under the extractor.

I hope this helps some folks.

steelap 06-17-2010 08:18 AM

From another thread, an alternative method of checking for corrosive primers:


Originally Posted by cowsblack (Post 142834)
the test is easy to do,you should try it. I used a bolt removed from an 1903 to pop the primer onto a piece of raw steel alongside a 7.62x54 known corrosive. the corrosive turned rapidly to rust with no rust or change on the AYR.


Originally Posted by cowsblack (Post 142845)
remove the bolt from the 1903 rotate the cocking piece to expose the firing pin. carefully pace the case under the extractor claw pull back the cocking knob while holding against the steel plate rapidly let go of the cocking knob to fire the primer. wear eye protection!

I would use three section on the test plate - a known non-corrosive (say, HXP), a known corrosive, and the unknown.

Eye and hand protection would be advised.

NOTE: If this method isn't deemed safe, please delete!

"Life is Good!"

Unclenick 01-09-2011 05:43 PM

A couple of points:

Ed's Red is a formula derived from the old Frankford Arsenal formula that Hatcher said worked. It has both polar and non-polar solvents so it should work. These days I spoil myself by using Boretech Eliminator for its copper removal speed. It is water-based and will also get the potassium chloride in the bore dissolved. Note, however, Hatcher's old admonition to clean immediately after firing and again the next day with corrosive primers is probably a good practice to follow.

Second point: Hatcher says that in the Bureau of Mines engineering study that proved potassium chloride was the culprit, it was also found that relative humidity had to be above something like 68-72% or somewhere in that range to start. I'd have to check the exact numbers. So don't assume your primer test is proving non-corrosive if you haven't had a rainy day in awhile. Probably best to set the sample in a jar with a shot glass of water sitting on the bottom and close the lid. That'll get you 100% RH in a little while.

RobX 01-19-2011 01:32 PM

I would add a couple of things to this test: primers are LOUD. Use hearing protection. Also use eye protection; what comes out of the barrel is under pressure and could kick up dust or debris.

Ray Brandes 05-13-2012 05:21 AM

Rather than use a good rifle, I use an old take off barrel with the correct chamber.
Wearing safety glasses, ear protection and heavy gloves, I bust the cap with an automatic center punch. Caution is advised as the primer may try to back out.
The barrel still gets cleaned after so salts won't contaminate the next test.
I have only done this with a Garand barrel.
Regards, Ray

aka108 05-13-2012 09:04 AM

If I wasn't sure the ammo was non corrosive I would assume it was corrosive and then clean the rifle accordingly.

heckinohio 06-15-2012 08:28 PM

Seems to me it is best to assume all foreign surplus ammo is corrosive. I had some late dated .308 that rusted the gas pads on my new .308 barrel after one shot & 3 days under the truck seat.....not worth the chance with a good barrel!!!!! PJH

Unclenick 06-19-2012 09:18 AM

I had that with some 1982 surplus that was made by Sellier & Bellot. It was advertised as being non-corrosive, but the seller was wrong. I shot it for a week in Arizona, where the air is dry, and had no visible problem there. But after bringing the gun back to Ohio humidity, and despite having cleaned it well (I was trying a lot of different cleaners back then, but I'm guessing it may have been Shooter's Choice, but I don't really know; circa '93). After a couple of weeks back home, I got it out and found the bore evenly coated with rust. A lot of JB Bore compound was put to work.

A year ago I came across a box with about 700 rounds of that stuff that I still have. Finding it got me curious enough to write S&B and ask how the heck such late manufacture ammo could be corrosive. They explained that in the "iron curtain days" they did a lot of military contract manufacturing for foreign governments. When someone ordered millions of rounds of something, S&B made it to whatever specification they asked for. Thus, uncatalogued special components were made and used in some of these contracts. Why someone would ask to have chlorate primers made special in 1982, I don't know, but they did.

jimthompson502002 06-20-2012 09:07 PM

Actually, RWS and their Dynamit Nobel associates were producing "Sinoxid" (noncorrosive) primers as early as the 1920's, for both commercial and military applications. Most WW2 European military ammo intended for aviation use was noncorrosive.

Take a look at some of the Austro-Hungarian ammo for the M95 straight pulls around. Most of it is marked "sinoxid" and "Umrust", noncorrosive, and dated 1936 to 1941.

The above methods will work, but when I did my big machine gun book back in the 1980's, decided the smart thing to do was clean EVERYTHING, even KNOWN noncorrosive, with a detergent/ammonia/alcohol solution, similar to but stronger than "Windex", flush the barrel well right at the range, clean out the gas system and clean and polish the firing pin head and bolt face, and then clean regularly. The ammonia helps dissolve salts bonded with copper.

This worked even with an ancient Hotchkiss, firing the old 8mm. French round, albeit due to other issues, we quickly located another source of ammo.

Thing is, it also GREATLY reduces overall cleaning time, and cuts down on the stench of those grotesque solvents indoors.

The more water, the better.

We generally carried about three or four spray bottles for a typical session, and by the way, using it on a barrel while hot is particularly effective.

Unclenick 06-22-2012 02:58 PM


You need to try Boretech Eliminator. Water-based, eats copper faster than ammonia and has strong surfactants that get at the carbon that's layered over the potassium chloride, too. It's also non-toxic, biodegradable and has virtually no odor. The only drawback is that it attacks copper and brass so fast that a brass jag will color a wet patch blue faster than you can push the jag through the bore. So you need plastic jags or nickel-plated jags or the special alloy jags that Boretech sells for this reason (what they call their Proof-Positive jags) to tell when you are done. You can read more in this Precision Shooting article, though the product line has expanded since it was written.

Boretech also makes a carbon-only solvent that's an even stronger carbon remover called C4. A fellow who tried some on a bronze nipple off his BP muzzle loader said it worked so well the nipple was bronze colored again for the first time since he'd first installed it.

There is also a slower product I like called Gunzilla B10 CLP. It is vegetable-based, but if you leave it in a bore for a few weeks, every microscopic trace of carbon comes loose and falls to the bottom side of the bore (assuming it's horizontal) and patches out. So does rust. This stuff got known in Iraq for ending AR stoppages because even though it lubes, dust falls off of it. I'd expect that to be a plus in other full auto guns, too. Again, non-toxic, biodegradable, and it has only a slight odor. Nothing like your ammonia does. It just won't act on your copper vigorously like the Eliminator. Gunzilla now makes a companion product for it that's a copper remover, but I haven't tried it yet.

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