Tuesday, April 01, 2008

Some notes on corrosive-primed ammo

One of the things I picked up at the show the other day was some ammo, and- like almost all surplus 7.62x54r- it’s corrosive primed. This stuff has been covered by people before, but I still run into a lot of people who’re worried about using it in their firearms, so I’m going to say my bit about it again.

First, the stuff isn’t actually corrosive. When some of the chemicals used in the priming burn, they produce trace amounts of salts. Those traces are deposited in the bore and if not cleaned out do what salt does: attract moisture. Which causes rust. Some ammo, if not cleaned after properly in a humid environment, can cause rust in less than a day. Most aren’t that bad, but they will cause rust.

The real problem comes in because many of the standard cleaners used today will not dissolve and remove those salts, and if you don’t know that and oil the bore and put it away, it’ll rust under the oil.

There are a number of things you can use to clean this fouling out, and if you want to start an argument at a gun board post something about it: in short order you’ll be told
That works.
No it doesn’t, but this does.
That’s crap, you’ll ruin your gun.
Just clean normally, no problem.
You need ammonia!
No, you need vinegar!
No you DON’T!
The most basic way is hot water with a touch of soap. Use a swab or brush to flush this through the bore, then dry it and oil it, just like a lot of people do with muzzleloaders. Personally, I don’t like flushing soapy water through my Mauser/MN/Tokarev/whatever*, but a lot of people use this method quite happily. I’ve seen a lot of people use Windex(spray it down the bore after shooting, wet patches then dry and oil). The two stuffs I’ve personally used that seem to work very well are a mix of one part sudsy ammonia to four-to-six parts water, and Ballistol mixed 1-to-10 with water. I prefer the Ballistol mix, it doesn’t smell nearly as bad.

With either of those, I take a small bottle of it, some patches, oil and a cleaning rod to the range. After I’m done shooting the rifle, preferably while the barrel is still warm, I pull the bolt, wet a patch with the mix(wet, doesn’t have to be dripping) and push it through. Wet a second, run it to the muzzle, then back, then out. Use a damp patch to wipe off the bolt face, then dry it. Run a couple of dry patches through the bore, then an oily one, wipe the bolt face with oil. That’s it. I usually do a ‘regular’ cleaning at home as this doesn’t get rid of copper fouling, plus I like to wipe out the action with my usual cleaner no matter what ammo I’ve used. And doing this should keep things safe if you can't clean that day; just to check I’ve cleaned a rifle at the range this way and left it for several days(checking it very carefully each day) with no rust, but Oklahoma isn’t generally too humid(generally, I said, there’re days it feels like you could wring the air and get drips); in a more humid area I’d do the regular cleaning soon as I could after getting home.
Please note: if you’re firing a gas-operated semi-auto, or for you lucky folks a select-fire or auto, you also have to clean out the gas system: a rusted-shut gas port or stuck piston is a Bad Thing. Very.

This has worked very well for me for years. Sometimes I’ve forgotten the rod or something and had to put off cleaning until I get home, in which case I first wipe out the bore with the mix, then standard cleaning.

I have also(again, checking very carefully for days after) tried just using a good copper solvent cleaner when I get home(Sweet’s 7.62 for one), and had no problems. The only thing you have to have is something that will cut loose or dissolve the salt traces so you can flush them out. In the case of a semi-auto, I used a big patch(or small rag) wet with suitable cleaner to wipe off the piston, out the tube, bolt carrier, etc.

In the case of a semi-auto pistol, I field-strip it at home and after cleaning out the barrel take some patches or a rag and wipe down the inside of the slide, the feed ramp and anywhere else I think some of the fouling might have snuck on- or into, then the normal cleaning and oiling. May not be necessary, but I do NOT want to rack the slide one day and find little communities of rust growing. Or a slide that won’t move.

*When I first started shooting milsurp rifles, I once cleaned a Mauser-first one I owned- by the hot water method: flushed it out, brushed, flushed, dried and oiled. Damn good thing I pulled it out about a day later just to check, as there was rust growing the bore. This caused a severely sick feeling in my stomach and a prolonged session of language practice as I grabbed the rod, brush, etc. and proceeded to give it the scrubbing of its life. By some miracle I caught it early enough that there’s no visible pitting, but it seriously pissed me off. And I haven’t trusted the water method since.


Daniel Newby said...

Would alcohol work? It's polar enough to dissolve many salts, but ought to be nonpolar enough to diffuse through any oily crud that might later get laid down on top of it. Besides, you can't drink ammonia or vinegar in an "emergency".

Anonymous said...

It isn't rocket science.

You'll need a small container of warm tap water with a little bit of dish detergent or hand soap in it. (My daddy used to shave some Life Buoy Soap in it with his pocket knife.) A pile of cleaning patches and a few paper towels or flannel rags.

Now use the soapy water on the patches to clean the bore and the bolt. Rinse. Repeat until the bore is clean. Dry it with clean patches. Now oil the bore and internals like your daddy showed you. Wait, that was my daddy.

If all you've got is cold water it might take a few minutes longer. Do it.

I had about 1500 rounds S.African corosive, mercuric .303 Brit. dated 1943. I love the stuff, my Long Branch #4 loves it too, and will shoot it eezackly where I point it. Got it free from a buddy who's scared as a little girl of those Scaawy Cowwosive Buwwets. I'm down to about 1100 rounds now. Lord, I'd love to get some more.

Gerry N.