There's probably some kind of moisture involved.
But the "invisible" chemical residue from Pyrodex can sometimes be notorious for damaging metal. Mixing that with humidity can really wreak havoc.
I would try the Eezox. Since it's heavier than water, the water can't permeate it to get below it.
Whereas with a coat of oil, that will always float on water which allows the water to get underneath it to cause rust.
Last edited by arcticap; September 25, 2012 at 11:09 PM.