Figure you will be able to get about half the amount of guns in a safe as what they claim. Scopes, bolt knobs, etc... take up room. If all you owned was single shot shotguns then you could store the # they claim. If you have 10 guns now then get a safe that will hold a claimed 30 - 40 guns. As HellsAngel stated you will put other things in there besides just guns and you will buy more guns so they will need a spot in the safe as well. It is far cheaper to spend more now for the extra room in one safe than having to buy another entire safe in the future.

Fire ratings depend on where you will keep the safe. A basement would require a higher fire rating than one up stairs on an exterior wall due to the heat building in the center of the house and remaining hot for an extended period of time and the possibility of the house collapsing to the basement and burning.

Keep in mind that the better you go with fire ratings you will automatically get better security. They go hand in hand with higher prices. Buy the best safe you can afford with ample storage for future purchases.