The reason to get a safety deposit box is twofold: 1) A place to store them, if you want to store outside the home; 2) Costs less per year than paying insurance on high-value revolvers. It is a risk, without insurance, of course, but less than keeping at home.
Banks, including mine, are very anti-firearm, and so they tend to frown upon keeping firearms in the safe deposit box. So, don't tell 'em.
In fact, it states that prohibited items include firearms and cash. Other than coins and jewelry and important documents, what else are you going to store in a safe deposit box, other than firearms and cash?
Folks, those of you who have safety deposit boxes, especially particularly large ones, what do you keep in them? Once, when I asked this of a teller, when I got my box out, knowing full well I store firearms in it, what others keep in their boxes, and she had absolutely no idea!