I know of situations where safes that have been bolted to the floor were still ripped out of the house. The best idea is to buy a cheap safe that can be removed. Add an old car battery or two for weight. Hide your firearms someplace within the structure of the building.
1. Concealment is a great first line of defense in a home situation. I used to have a small safe bolted to the slab under the stairs of my house before I moved. I piled firebrick on the top and sides for more fire protection and then cut the bottom out of an old cardboard box and put it over the top.
2. If you can, always install the safe yourself. I know of several people who had a safe professionally installed and then professionally ripped off a few months later.
The old bait and witch routine I see.
Good idea
BAD idea with the car batteries. Acid fumes inside your house are not a good mix. If you like the idea of adding high mass low volume, go to a tire shop and buy their scrap tire weights. Better still, deck the floor with loaded ammo cans once you’ve bolted it down. You do have more than a couple boxes, right?
Another idea is to take an ordinary closet, back the door and inside walls with plywood, pin the hinge side, and a decent deadbolt. Chopping through the door or walls just gets to more resistant plywood. Put it on its own alarm circuit.