I've always used WD-40 and never had a rust problem, ever, on anything. I have a gun safe that has one of those aerosol misters for air freshener, the type with a timer. I found a small can of WD-40 that fit instead of the air freshener and reset the timer. Every 18 hours a "pssst", and a nice cloud of spray settles on everything in there. 40+ guns and twenty years later and zero issues.I'm adding you to the list!
I will be back with a detailed response as soon as possible. I have my hands full right now.