It is absolutely essential that the safe be bolted down.
A lot of lower end gun safes can be defeated by a pry attack due to little to no plate steel in the door along with thin 12 gauge steel used for the body so if the perp(s) can lay the safe on it's back they can get some very good leverage on the safe thereby defeating it.
On some better safes another reason for bolting it down is due to the fact that the safe is very door heavy and when the door is swung open can result in the safe actually tipping over.
My safe is a American Security BF 66X36 that weighs 1250 pounds empty and Amsec tells you in the safe literature that it must be bolted to prevent tipping.
I had just done a flooring remodel of my home right before my safe arrived and since the floors are a laminate I had the flooring contractor place a 4'x3' pad of very hard porcelin tile in the corner of the room specifically to place the safe there.
The safe and vault company that I paid to bring this beast in placed it on the tile and then drilled four holes through the predrilled safe floor bottom and put in four half inch diameter by four inch long Red Head concrete anchors and bolted it down.
It is very secure in it's present setting and since these safes have outer hinges so you can get a full 180 degree door swing I can tell you if the safe had not been anchored the first time you swung that heavy door open the safe would have landed right on you.
The door is a full half inch of plate steel backed by a steel encased one inch thickness of a concrete material inside the door.
HEAVY.
