Gun Cleaning, Part the Fifth: Corrosive-Primed ammo

Lots of military surplus ammo out there, especially in 7.62x39 and 7.62x54r. It costs less- sometimes MUCH less- than commercial, often can be had in 'spam' cans in which it can be stored for decades, and it works. Just the kind of thing for practice, and maybe stashing some away just in case.However, there is a slight problem: rust.

Just to cover the matter, the ammo is not actually corrosive; it's called that because of the effect of some of the residue left behind by the primers. One of the chemicals used in primers for a long time(and in Europe still used for some military ammo), when it burns leaves traces of salt behind. Salt itself isn't corrosive, but it attracts moisture, which WILL cause rust.

So you have to make sure your cleaning flushes the traces of salt out of the bore and- especially in semi-auto rifles- action. What complicates this is that most commercial CLP and bore cleaners don't do this well, which has caused many people to clean their rifle, look at it a few days later and find rust in the bore.

And some ammo is worse than others. For instance, there was some 1960's-production German 8mm Mauser ammo available for a while that was fairly awful in this respect. I'd used some of this, and knowing it was corrosive primed, cleaned appropriately. Which turned out to be insufficient for this stuff. Two days later(no later, thank God) I pulled it out to check, and found rust in the bore. Which occasioned an amount of screaming and cursing and immediate recourse to EVERYTHING I HAD to scrub it out. I found it before it'd had enough time to do real damage, but a lot of people have not been so lucky.

So how do you clean the stuff out? Same tools(patches, brushes, rods) as any other, but a different cleaner is needed. The basic is water; it will dissolve the salts, flush them off the surface, and let a patch carry them away. If you use straight water, hot is best, as it'll both help flush the stuff out, and warming the barrel will help it dry faster.

A lot of people add ammonia. Doesn't take much, maybe one part ammonia to ten of water, though I've heard of people using as strong as 1-to-5 just to be sure.

I've been told water with a little vinegar added works well.

A favorite with a lot of people is Windex. Yes, the glass cleaner. I have known people who swear by it. Supposedly the version with vinegar is best.

About the best cleaner I know of for this is Ballistol. Works straight for general cleaning and lubrication, but for this purpose it was designed to be mixed with water(proportions on the can) for cleaning this kind of fouling. It works, it doesn't stink or(that I've noticed) mess with your skin like ammonia. Good stuff.

Thompson Center No. 13 Bore Cleaner. This stuff was made for cleaning muzzleloaders and other arms firing black powder. I've tried it, and it worked quite well.

As noted, plain hot water works. George McDonald Fraser, in one of his books*, wrote of the British Army 'boiling out the rifles' after a day involving shooting. The Brits actually issued a special funnel(one per squad, I believe) for the purpose: had a short hose with a nozzle to fit into the chamber; set the rifles upright, take some hot water and flush out the barrels, then dry and oil them.

With most corrosive-primed ammo, it's not really a big deal to clean. The ideal is at the range, after you're done shooting(description is for bolt-action rifles), remove the bolt. Get a patch damp with your chosen cleaner, and push it through the barrel(or pull it through if using one of those cleaning 'rods'). Do that again. Push a dry patch through, then a lightly-oiled one. That's it.

Dampen a patch with cleaner, wipe off the bolt face and the front section of the bolt. Dry, then oil.

After you get home, do your normal post-range cleaning, and it should be fine. If you can't do the initial cleaning at the range, do it after you get home, followed by the usual. With most of the ammo you might run across, this should take care of it. Though it doesn't hurt to check things the next day or two, just to be sure(again, really glad I did it after that 8mm ammo).

With any of these, remember that after you flush out the barrel, you need to make sure it's thoroughly dry, then use some type of oil or CLP to prevent the bare steel from rusting.

On actions, and things like the gas tube on a SKS, I prefer the Ballistol mix; it does a fine job of cleaning the residue out, and even though there's water involved I've not seen it promote rust(do dry and oil after, just to be on the safe side. And you can use straight Ballistol for that).


*Quartered Safe Out Here, excellent reading. A bit on the Enfield rifle:

And she did, thirty years old as she was; treating her right consisted of keeping her “clean, bright, and slightly oiled” with the pullthrough and oil bottle in her butt trap, and boiling her out after heavy firing.