Think about the videos of crazy people crashing into convenience stores, throwing a chain around the ATM and driving off..
I look at your question this way:
1.) There are many products on the market that can address your rust concern. And, no, I believe as long as the guns are dry, the temp in your garage will never get down low enough to affect them.
2.) Most every good gun safe I've ever ran across provides holes in the bottom to secure said safe to whatever it is sitting on. To me, an unsecured safe in the garage is only one chain & a pickup truck away from disappearing from my possesion. Think about the videos of crazy people crashing into convenience stores, throwing a chain around the ATM and driving off..
What do you mean by dry? No oil on them? I would think you would want a protective coating of oil on them to prevent rust.
No, No. By dry I was referring to not humid. I tend to only lubricate the moving parts of my firearms and I don't use oil; Tetra-grease is my preference. And I don't oil down the exterior metal parts but I do run silicone down the barrel if I don't expect to shoot it in the near future.
Gun Grease, Tetra, 1 oz.