I've been researching this topic as one of my ARs is chambered in 5.45 x 39 and I get Russian surplus ammo for like 25 cents a round. I try not to shoot corrosive ammo but sometimes that's what I get. I always completely tear down and clean my gun after each use. Water works! I simply pop the two roll pins on my AR and take the upper/lower apart, remove the carrier and charging handle. I take the cap from my M7PRO cleaner bottle and put it over the muzzle and take steaming hot water and pour it with a funnel into my chamber and let it stand for a few seconds, flush, repeat etc.. and it clears a lot more gunk out of my gun than if I just shoot M7 or similar cleaner down the barrel. After the water, I blow some air through to dry, run a few dry patches through, then clean with a light bore brush, some M7 cleaner on patches and finish with a touch of lube on a patch and my barrel is clean and bright and after thousands of rounds still fires reliably and no signs of any rust or corrosion.
