Hmmm. The Lone Ranger used silver bullets- you got a silver GUN?
We need a hint what the reciever is made of- and trust me, you do not want to fool with ANY solvent that would dissolve metal. Not if you value fingers and lungs.
It MAY be possible to REDUCE the visible damage by polishing (Flitz is pretty good)
However, we need some more info and some pics.