I suggest getting a safe that has a decent fire rating, waterproof to a certain degree and has a total lifetime warranty on the entire safe. The better safes have a good rated lock. I would stay away from biometric and go with a standard combo or electronic code lock. I say this with experience. For a 40 gun about 60 inches tall gives enough room to move the shelves around. Quite a few models to choose from like Liberty, Sports Afield, Champion are popular safes that have “series” that have different features and quality levels which span a wide price range. There are quite a few add-on features you can get. I like the motion activated lights, power outlet with USB ports and audible wrong code alarm. Depending on where you live you may want to plug in a good dehumidifier. I would place the safe somewhere out of the way in a room where the temperature and humidity doesn’t change very much.
You can spend whatever amount you want to spend just like anything else. But a decent 40 gun safe will be at least 600 lbs plus. If you buy a safe from a “big vendor” like Home Depot or Cabelas they will only deliver your safe to your curb on the street. If you try to install that size safe yourself without specialized equipment you could easily damage your home or yourself. I did it once with a 600 lb safe because it was level into the room where I installed the safe and a short distance. But I had ramps and a heavy duty appliance dolly with a helper that was used to moving heavy appliances. I would suggest buying the safe from a large and reputable local safe shop that has a good selection that you can go in and swing the doors, check the layout. They will deliver and install the safe in your home with the proper equipment. It is well worth it believe me. I suggest taking the time to look around and figure out exactly what you need and want.
You can spend whatever amount you want to spend just like anything else. But a decent 40 gun safe will be at least 600 lbs plus. If you buy a safe from a “big vendor” like Home Depot or Cabelas they will only deliver your safe to your curb on the street. If you try to install that size safe yourself without specialized equipment you could easily damage your home or yourself. I did it once with a 600 lb safe because it was level into the room where I installed the safe and a short distance. But I had ramps and a heavy duty appliance dolly with a helper that was used to moving heavy appliances. I would suggest buying the safe from a large and reputable local safe shop that has a good selection that you can go in and swing the doors, check the layout. They will deliver and install the safe in your home with the proper equipment. It is well worth it believe me. I suggest taking the time to look around and figure out exactly what you need and want.