Building a 10 gauge safe within your Liberty FatBoy
When you speak of remodeling your gun safe I think of some way to add more security and/or more steel. This is a Fort Knox Defender 7241 that would normally have two full size top shelves. Instead they've designed this 28" Cab Box designed as a second lock box inside your gun safe, then taken the top shelf and used it to create a new floor surface. Now if the gun safe was bolted in all four corners and the Cab Box was bolted using long concrete lag bolts (Tapcon), in all four corners inside the Cab Box, that secondary safe would be pretty secure and still portable by removing the lag bolts. But you would have to drill four new holes in the floor of the gun safe which may possibly void a warranty. Fort Knox is so open to flexibility, they would probably predrill the holes for you if notified prior to the gun safe leaving the factory.
My thoughts to you owning a Fatboy. This type of application may not be an option for you since the height of your gun safe is only 5 feet tall, allowing for only 1 full top shelf. However, the Cab Box may be more practical for you to use vertically and even using, for example, the back left bolt hole in the Liberty FatBoy to bolt the Cab Box in place and probably another bolt kiddy corner inside the Cab Box which may possibly void a warranty again (check with Liberty Safes first, they are flexible as well to a certain degree).
The Cab Box in these pictures is 28" wide. It also comes in 20" and 24" in the same design. They also make a box thats 45" long used for shotguns up. Then there is also the Fort Knox Personal Pistol Box and the Fort Knox Original Pistol Box which are smaller separate lock boxes used for single, maybe dual pistol storage. Every thing in this Fort Knox series is 10 gauge body and 7 gauge door. Maybe this isn't worth the risks and troubles for the amount of steel added. Maybe you can take these thoughts in your own direction, or maybe I'm way off basis.
"As Iron Sharpens Iron, So One Man Sharpens Another"