Machineguntony....If you just do a little locating of studs in your walls, and drill 3/8 holes through the back of the safe to correspond, you can put 3/8 lag bolts into the studs. Half a dozen of these and any bad guy will need some serious power to pull it away. Combine it with some expansion shields into a concrete floorl and it's pretty much there to stay.
Of course if you have one lined with firebrick this could be more of a problem because of the depth of the safe walls, but there are always ways around this. I doubt there would be any loss of integrety to the safe.