Author Topic: Primer on Corrosive Primer Chemistry--if you hate chemistry you’ll hate this  (Read 7904 times)

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Offline Phosphorus32

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Many of us shoot military surplus ammunition with corrosive primers in our SKSs (M43, you're shooting collectable ammo?!, or M67), Mosins, Mausers, etc. I all too often see misinformation on various boards, and especially on Facebook, and I figure every board should have an informative discussion of the subject, so here we go.  I apologize ahead of time for perhaps getting too deep into the chemistry, but I'm a biochemist and I actually enjoy this stuff  :))


Sodium chlorate, NaClO3, or potassium chlorate, KClO3, based primers

The chlorate anion, ClO3-, is the main active ingredient and serves as a the percussion sensitive oxidizer in this type of primer.  Chlorate is only slightly more reduced (by one pair of electrons) than the even stronger oxidizer sodium perchlorate NaClO4, used in solid rocket fuel formulations.  Chlorate is the source of chloride, Cl-, in the spent residue from the primers, i.e., the sodium chloride (table salt) or potassium chloride, which are the active “corrosive” ingredients.  Humans need sodium, potassium and chloride, so these residues are harmless from a human health perspective.  (I find it a bit ironic, that we are more concerned with our rifles than our own health in respect to the inhalation of lead aerosols from the discharge of modern non-corrosive lead styphnate based primers, but that's another subject).

The use of the terms corrosive ammo or corrosively-primed ammo (more specific) is a bit of a misnomer and often leads to confusion.  In the chemical hygiene sector, the term corrosive usually refers to something acidic, like battery acid (sulfuric acid), or muriatic acid (hydrochloric acid) and hence in need of neutralization.  This is not true in the case of simple salts like sodium chloride and potassium chloride.  They are pH neutral (neither acidic nor basic), their corrosiveness is based largely on their ability to attract water from the air and trap that water adjacent to the steel surfaces of the bore (these salts are hygroscopic).  Water is needed to mediate the oxidation of metallic iron to ferric oxide (rust) by oxygen in the air, so trapping water and maintaining it in contact with the iron of the bore is the problem posed by the corrosive primers.  To prevent corrosion, these salts need to be removed from the bore.  This cleaning should take place as soon as possible if high relative humidity (over 50%) conditions are in effect at the time of firing your rifle, or during storage thereafter.  If one lives in an arid climate, then cleaning is less urgent, but should still be done soon, because relative humidity varies with the weather and time of day (it is temperature dependent), even in arid climates.

Inorganic salts like sodium chloride and potassium chloride are very soluble in water and slightly soluble in ethanol or methanol.  Water and alcohol are examples of polar solvents, and that is the general type of solvent needed to solubilize any type of salt (salt is used in the general sense here, not specifically referring to table salt).  Non-polar solvents like petroleum distillates found in aerosol or liquid gun oil formulations, paint thinner, mineral spirits, etc. are not effective at dissolving salts.

The cheapest way of dissolving and removing salts is the use of water. Of course you don’t want to leave any water behind when you’re done cleaning, because attraction of water is the problem with salts in the first place! Using hot water can aid in evaporation, as long as there is enough volume of hot water to heat up the barrel, and thus speed drying. Following up with a wet denatured alcohol (ethanol) patch or two is another method since water and ethanol are completely miscible and the ethanol is more volatile, i.e., evaporates more quickly. If you prefer a commercial cleaner, then choose something like Hoppe’s No. 9 Solvent, which has a lot of ethanol, and run a series of soaked and dry patches through your bore. Such a procedure is probably sufficient to dissolve and wipe out the relatively low amount of salts produced by corrosive primers. If you’re a black powder shooter, Hoppe’s No. 9 Black Powder Cleaner is an even better alternative to their regular Solvent formulation, since it’s about 80% water.  Just follow it up with dry patches and a water displacing solvent like standard Hoppe’s #9 Solvent. It’s not my intent to endorse Hoppe’s products as the ultimate solvents, they’re just widely available examples of suitable products.  I like to finish my bore cleaning with an oiled patch. Then I run a dry patch through the bore before heading to the range. Of course your preferences may vary.

Aside: Windex almost always comes up in "corrosive ammo" discussions, and this cleaner is okay as the primary salt removing solvent, since it’s mostly water.  However, it needs to be followed up with a water displacing solvent, as discussed for the water or black powder cleaner methods mentioned above.  The Ammonia DTM (actually just dilute ammonium hydroxide) is a mild base. At higher concentrations ammonium hydroxide is uniquely effective at removing copper fouling--but again, that’s another chemistry subject.  I don’t think there’s sufficient ammonium hydroxide in Windex to be particularly useful in removing copper. If copper removal is your aim, then you can use Sweet's Bore Cleaning Solvent, or simply dilute some household ammonia 1:4 with water.
« Last Edit: October 14, 2015, 07:14:57 PM by Phosphorus32 »

Offline Dannyboy53

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Very interesting (and I hated HS Chemistry). Good timing too Phosphorus32, just before I fire those M67 rounds. I have an air compressor that I incorporate into cleaning my firearms, I know it's cheating but it's a big help.

This should be a sticky...danged good info. Thank you for taking the time for this Jon!

Offline Phosphorus32

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Thanks Danny  :)

I don't think anything that makes cleaning easier and more effective is cheating  clap1 Compressed air will certainly speed drying which is important  thumb1

Offline jjjxlr8

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This needs to be a sticky on just about every gun forum that I've been on!!!

Offline Loose}{Cannon

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This needs to be a sticky on just about every gun forum that I've been on!!!

Done... 


Great work Phos....   So If I clean the barreled action while Im taking a shower, is that bad?   dance2
      
1776 will commence again if you try to take our firearms... It doesn't matter how many Lenins you get out on the street begging for them to be taken.

Offline Phosphorus32

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This needs to be a sticky on just about every gun forum that I've been on!!!

Done... 


Great work Phos....   So If I clean the barreled action while Im taking a shower, is that bad?   dance2

Thanks jjj and LC!

If you want to shower with your rifle, who am I to judge rofl

Offline Dannyboy53

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LC just make sure the chamber is clear when you cycle the bolt.  :o  :-[

Offline MEBears

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Excellent write up!  thumb1

Offline HillHopper

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Man... wish I'd read this before I bought Natasha. Shelled out for a bottle of Windex on the way home because I'd picked up some M67. Bottle of Windex isn't a major expenditure, but by the end of that day it felt like one. They should have a post like this on the Mosin-Nagant board I'm on . I'll look & see if they do. My buddy who's big-time into M-Ns talks about Windex like Moses brought a bottle of the stuff down from the mountain.

Offline Dannyboy53

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I have had a hard time from friends/relatives over the years for incorporating WD40 in the cleaning of my firearms, but it was developed solely with water displacement in mind. I still have it in my "arsenal" of cleaning & lubricating products.

http://wd40.com/cool-stuff/history


Offline Greasemonkey

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Man... wish I'd read this before I bought Natasha. Shelled out for a bottle of Windex on the way home because I'd picked up some M67. Bottle of Windex isn't a major expenditure, but by the end of that day it felt like one. They should have a post like this on the Mosin-Nagant board I'm on . I'll look & see if they do. My buddy who's big-time into M-Ns talks about Windex like Moses brought a bottle of the stuff down from the mountain.

I use windex..I use hot water, what ever is available... the biggest single thing regardless of your cleaner/fluid of choice, is to clean it, clean it in a timely manner, and clean it all correctly, gas system included. Find what works for you stick to it and do it. All your really doing is getting the salts out to prevent corrosion, that is the key thing. The lubrication part that follows, pick your poison, motor oil to space shuttle rated uber stealth tactical lube, whatever works best for you, again, just lubricate it.  thumb1
I'm going to make him an offer he can't refuse......

Leave the gun, take the cannoli.

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