The old military ammo with the big copper primer cup was invariably CORROSIVE and the mercury wrecked the brass. In a climate like Florida or the eastern seaboard of Australia, ONE night without proper cleaning will result in bores taking on a brown and crunchy appearance.

NOTE: Even hard-chromed bores are NOT immune, just a bit more resistant. ONE micro-fracture in the chrome skin and the corrosive salts will start doing their thing, UNDER the chrome. Once it starts on the steel substrate, you will quickly see chrome starting to flake off.

It was normal practice, at least by those who wanted their expensive machinery to last, to use BOILING or very hot water as a bore cleaner. There were suppliers of nifty funnels that ran a fair way into the chamber and had an “anti-splash” shroud at the top of the funnel to keep water out of the woodwork. Keep pouring the water through until it runs clear and you should have removed all of the soluble salts (Chlorides) that eat your barrels. The heat transferred to the barrel steel will help dry it out pretty much before you can run a dry patch through.

In a real military situation, rifles were cleaned and oiled as soon as possible after firing and then re-cleaned several times over the next week. Military “gun oils” are often a much more complex brew than sewing-machine oil.

This water and oil regime works well on AKs and SKS’s firing any ammo. DO NOT neglect all of the components in the gas system; piston, spring, cylinder, regulator, etc. At the very least, hose out the bore and ALL working parts with one of the good commercial corrosion-inhibiting “oils”, before packing the gun away for travel home. As soon as possible after arriving home, strip and thoroughly clean and put away in the usual secure place, away from temperature changes.

“Windex” and similar products are to be used only as a last resort and then only until PROPER cleaning materials are available.

Simple rule: Treat ALL ammo as corrosive, clean with that in mind and your guns will last a LOT longer. Good cleaning gear and timely use thereof, is a LOT cheaper than re-barrelling or rebuilding a rifle.