I have a leather sling on one of my guns, and the brass (I assume) hooks and rings react with the leather/air and corrode a little bit. The stuff looks like a mashed up green crayon. Is there anything that ya'll know that can keep that corroding/reacting from happening or at least slow the process?

Not sure if this will work but mywifegets areaction from some metalsshe applies a coat of clear nail polish on the such things that may come in direct contact with her skin and no problems.

I would guess it's moisture in the leather, maybe use a leather conditioner or sno seal to keep the sling from absorbing moisture and if you end up in the rain take the sling off the gun to dry out real good.

That green stuff is called verdigris. I think that means green stuff in french or something

Thanks for the ideas guys! I don't think it's moisture, but I took the sling off and I'm going to pick up some brass polish and try the sealer for the leather.