I decided to take a look at the revolver I’ve kept loaded for a long time. It is a Taurus 66, .357 Magnum revolver. It was my first handgun and has been a reliable, accurate home defense gun.
I opened up the safe for the first time in almost a year and went to unload the gun. The extractor lever wouldn’t move. I finally got it to move and found the problem right away:
Nickel cases in the stainless steel chamber, plus a little moisture and voila! The perfect recipe for corrosion. The green is probably from the brass (under the nickel coating).
I will have to be much more careful about not trapping any moisture in those cylinders! Once it is in there, crevice corrosion (where moisture and air are trapped in a small crack, like between the casing and the cylinder) and dissimilar metal corrosion take over.
I am working on cleaning up this mess. The corrosion did not etch deeply at all, and I am confident that the gun will work flawlessly.