On the outside of a weapon I have used various waxes for a long time. They protect and preserve the metal and seal the stock from moisture while adding to the sheen. I've that most products with carnuba in them work just fine. For the metal though I found a product called 'Rust-Prevent-It' that is exceptional. It's a spray on production that is allowed to set for a bit after application and the excess wiped off. It is impossible to remove it all and it has possitively stopped fingerprinting of my weapons. That is the rust from handling. It seems to last forever but is totally removed by any solvent based product as are most gun cleaning solutions. I bought the last of it from 'D&R Sports'. Good luck..
