The advice about gunsafes is probably right but you do not really need the commercial safe nor can you get it upstairs in your house (or place one anywhere but on a concrete floor most likely). If you ever move to another home you have to accommodate that monster. You will need to remodel the insides of the safe also.
Fire ratings are almost always not an issue as I would never feel safe shooting a gun that had been through a serious fire nor would that be a priority to me if my house burned down. And that does not happen very often. If I ran a pawn shop I would be looking for a commercial safe but I don't. However, if you can live with a big old safe in your garage and want to keep your guns there by all means go ahead.
Check out Rhino safes (
http://www.rhinosafe.com/bh6039.htm ), available at Tractor Supply (if they operate stores near you) at a very good price. Extra thick sides and good fire rating. I find that safe makers often hide or refuse to give details about the materials used in construction of the safe. Stackon is the worst.
Think about what this safe is going to do for you and what you need. I figure it keeps the smash and grab thief at bay and the guns out of the hands of those who should not handle guns. If a thief really knows you have valuable guns and wants them he can just haul away the entire safe, after all, you hauled it in.
One last item, your homeowners insurance most likely has a $1500 dollar limit on firearms so don't count on collecting much from them.