Well, if you'd still like to try muscling it yourself, consider stopping in at an equipment rental agency. These companies often rent heavy-duty moving dollies, complete with tank-like tracks that make moving up and down stairs a breeze, and usually include an appliance belt that helps secure your safe to the dolly.
Additionally, don't forget to check with your local moving companies. They'll need to know the weight of your safe and if you need to move it up or down any staircases, so they can figure out how many people they'll need to send; but this installation route is usually about as pain-free as they come.
And finally, feel free to look into piano movers. Ask them up-front if they'd be willing to tackle a gun safe, and make sure you tell them how much it weighs and generally how difficult the move will be. Some of them might not want to deal with moving your safe, but many won't even bat an eyelash. These folks are accustomed to moving expensive, heavy objects on a daily basis without causing damage.
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