If you know for a fact it won't be moved use silicone sealer under it, generously. It would take a jack hammer to move it. One of mine is a Winchester I bought from Sam's in the 80's. I have tried to find another one but today they are mostly 12ga steel and the door is rolled. The door on my Winchester is 1/4" steel plate. the walls are slightly thinner. Nothing like the quality of the current less than $1k safes.