I have two stack on dehumidifiers.
I was having issues with rust on my Savage rimfire rifles. Haven't had a problem since. I check them every couple of weeks and recharge them every three to six months (summer is worse, of course).
I use this in my gun safe to combat moisture:
Work great, I have been using this one for ovre a year.
Stack-on Dehumidifier, I live in South Florida and have to charge it every other day to keep it dry.
I disagree. I live in Illinois (climate as stable as our governors) and keep my safe in the garage. Granted, because I have no room in my house for it, but I have no problems with rusting.
Just make sure if you do put the safe in the garage you do bolt it down and put in one or two of these.
As others have mentioned you shouldn't be worried about it coming off, a little brass and/or steel wool and some oil will take it off. What you should be worried about is how your treating your gun. If it stays in a safe when not being used, meaning it's not a daily carry gun, then you need to get some kind of dehumidifier in there with it. I use two of these in my safe and they work great. If it is your carry gun then you need to break it down clean it more often. You should also consider where you carry it as well. Putting a barrier between your skin and your gun is more comfortable and keeps unwanted body oils off of the gun.
I use these in my gun safe. They work great, and they're relatively cheap! Had one for over a year and it's still going strong.