I investigate fires professionally, and I have seen a lot of safes in houses that were burnt to the ground. If the house burns to the ground, your guns will be ruined in any consumer style safe. Not until you get up to $3K or more are you really gaining any fire protection that will withstand a grounder. Pretty much any fire rating is sufficient for a gun safe in a metro residential city. I think the Liberty brand is one of the better ones.

A few tips...wherever you place the safe, elevate it a few inches off the floor. Best bet if you have something over 400 pounds is to build a 2x6 pedestal that spans several floor joists. Lowest level of the house, but slightly elevated. That way, in a grounder, you won't end up with a safe full of water. Don't store primer or gunpowder in the safe. A small amount of ammunition is okay, but not cases of it.