I looked at that option--primarily concerned about my kids and their friends. Instead, I spent a few hundred more and found a 14 long gun fire rated Sentry safe with an electronic lock for $450 at Academy (a sports and outdoors store in this part of the country). I mounted it in my closet, attached to the foundation.
Of course, my 8 yr son decided to see how much water the shower pan would hold (only as much to the bottom of the door). The shower is on the other side of the wall from where I mounted the safe. Only a week after busting my butt moving a safe in there, taking the closet door off, etc., I had to unbolt it, unload the safe, move it out of the closet, pull up carpet and baseboards, and dry everything out before I could put the safe back in. It's a relatively small safe, but still weighs around 500#.
On an off thread topic, I asked my son several years ago what he would do if he was at a friend's house and found a gun. He answered appropriately (it's loaded, don't touch, find an adult, tell daddy so he could yell at the irresponsible neighbor, ...). I asked my daughter who is two years younger (3 at the time). She hit the ground and started yelling STOP, DROP, AND ROLL!!!!.