The gunpowder?  The primers?  Just curious.

Primers

I have heard (I could be wrong or it might not be the whole story) that the corrosive compound is Mercury Fulminate.  Fulminate compounds are the magic ingredient of the primer that detonates when given a shock.  Mercury Fulminate is a type that (I've heard) is cheaper and easier to make than whatever type of metal Fulminate the US uses as Mil Spec.  As I understand it it's the Mercury that remains that is corrosive, I suppose it sets up a galvanic cell as is the root of all corrision when there is enough water present.  There may be other compounds causing problems too but as one can see at this site, Mercury Fulminate is no longer used in US primers.
www.aeroballisticsonline.com/ballistics/propellants.html
www.powerlabs.org/chemlabs/fulminate.htm

I think the mercury is the result of really ancient primers.  That was the stuff that ate brass.

The merely old primers deposited SALT in the the bore.

Dennis Jenkins

Quoted: I have heard (I could be wrong or it might not be the whole story) that the corrosive compound is Mercury Fulminate.  Fulminate compounds are the magic ingredient of the primer that detonates when given a shock.  Mercury Fulminate is a type that (I've heard) is cheaper and easier to make than whatever type of metal Fulminate the US uses as Mil Spec.  As I understand it it's the Mercury that remains that is corrosive, I suppose it sets up a galvanic cell as is the root of all corrision when there is enough water present.  There may be other compounds causing problems too but as one can see at this site, Mercury Fulminate is no longer used in US primers. www.aeroballisticsonline.com/ballistics/propellants.html www.powerlabs.org/chemlabs/fulminate.htm

Modern primers use lead stearate, non corrosive.  The old "fulmanate of mercury" primers left corrosive salts in the bore which would absorb moisture from the air and corrode the bore, unless cleaned well soon after shooting.  In the US we have been using non corrosive primers since the 40's for most all commercial and military ammo.

True black powder would also leave corrosive salts in the bore, but not a problem with pyrodex.  It was common to flush the bore with hot water to wash out salts and then clean as usual.

Some Chinese and other ammo is still corrosive.

flush the bore with hot water to wash out salts and then clean as usual.

i find that dont work too good. i shot old turkish 8mm out of my mauser (big mistake) cleaned it with hot water then cleaned with clp. made my bore nice and fuzy. i read on these forums to use amonia to clean the barrel after shooting corrosive ammo and it works. no rust

im not sure what component in the gunpowder or primer does it. But a salt is left in the barrel, by itself it is harmless. It is the moisture in the air that reacts with it to create an acid that then reacts with the metal.

neutralize acid add a base. Ammonia will do it.

Just use the old smelly cans of g.i. rifle bore cleaner. I muast have about 25 cans left. I don't think they sell it anymore. I don't know what I'll do when I run out, I love the stuff, it's made to dissolve corrosive salts and protect the bore (but it smells like hell) I just shoot the turk 8mm/ p.o.f. .303 or whatnot, swab the bore (keep it good and wet for a couple days to catch any corrosive compounds that may leech out) dry swab, then another wet patch of bore cleaner and leave it that way if you're gonna shoot in a bit, if not, dry and grease/clp her. I've been shooting corrosive more than anything else in my M91, M48 and enfields and never a sign of damage or trouble. Don't listen to some of the doomsday sayers, proper maintenance will render any percieved problem with surplus corrosive ammo non-existent.