Whatever you do, don't get one of those fire-resistant "document safes" from Office Depot or anything like that. The reason they're fire-resistant is that they have layers of moisture-impregnated material in the walls and door of the safe. That keeps the inside of the safe damp, and it will absolutely ruin the finish on your guns.
That quote is from an old thread I found while trying to do some research. I have one of those Sentry document safes that I used to use for documents and for my 686 before I got my large safe. I can certainly attest to the fact that there is moisture inside. I didn't know about the moisture impregnated material and fought it for years. I had the safe in my closet which was in the bathroom and I figured moisture was getting in somehow. I went through a lot of dessicants trying to keep the documents dry. I had not shot in a while and didn't think to check my gun. It was zipped up in its cloth triangular pouch and surprisingly remained mostly undamaged after a few years locked up in a moisture rich environment. Some surface rust that came off with extra fine steel wool and it looks great.
Another thread got me thinking about that empty safe sitting in the garage. This morning I had to rush home because my wife heard noises upstairs and I was not too excited about entering the house unarmed. I had been on the way to drop off my daughter at school then to work and am not able to carry at either. That discussion here. The question is, can I make that safe safer for gun storage? I was thinking about getting an old used revolver that I wouldn't have to worry about too much but that I could get to in the garage before I entered. I'm not worried about the fireproofing or someone stealing the safe itself, I just want to have a gun in the garage that is locked up away from kids. I think a Bud's Model 10 special will work nicely for this purpose.
The safe is sitting on a metal shelving unit with a wire mesh shelf so if I drilled out the mounting holes in the bottom wouldn't that at least allow the inside of the safe to breath and not hold moisture in? Any other ideas?