I have had to store many firearms long term, at times not so well climatically and have found Hoppe's gun grease to work well for decades. Not sure if it is the same as it has always been (stuff I use is a clear amber tinted "paste"/thick gel), in the all orange tube that I have. I'll also treat my reloading dies and exposed steel parts of my presses with Lee Liquid ALOX. Dries to slightly tacky finish, and holds up very well. ALOX is a popular ingredient in many anti-rust/anti-corrosion compounds, and just so happens to make a great bullet lube too. Good luck.