I've done several of these for new houses. Most of the time we use bank vault doors but one we actually did a hidden door behind a built-in bookcase with a secret latch. It was like building something you see in the movies, which was fun.
Make sure that you look at the reviews for break-in times on these safes. Unlike your irreplaceable documents, you won’t care as much if the guns burn up as if some criminal steals them and they’re on the streets. Except for the black powder collector’s weapons, which are a different story.
Guns are not here, only thing in the house is a glock 23, Mossburg 500 and. 44 Magnum special. I doubt I’d get a chance to shoot though, I have two German Shepherds that have been professionally trained to maul you if you look at my wife or kids wrong(sort of joking.) That’s on top of a security system with 7 cameras. The safe was to store the guns when people are invited in the house.
I still like the concept of a gun vault/room over a safe if you can swing it. You can do all of your gun work (cleaning, reloading, etc) in a safe environment that isn't your kitchen table or garage bench. It also minimizes the chance of you accidentally leaving something out where the kids could get it because the weapons never leave the room.
Really don’t have the room to dedicate but it would be cool. Knowing my luck I’d get locked inside.
