Wall and floor safes are available in different sizes. My wall safes are not large enough for 5 firearms, but there are deeper/larger versions.
This one is a V-line. It is a reliable "safe" (security container), thick steel, Simplex lock. Being mounted between two wall studs prevents easy removal. The Simplex lock is super-fast, and very reliable. The combination allows for a various number of button pushes, with simultaneous pushing of buttons possible, so the number of combinations is easily enough to thwart a child or basic robber. Yes, it can easily be defeated by a determined person, but all locks can. The advantage to this one is you would either have to have LOTS of time to defeat it, or have to saw part of my house out to take it with you! AND you would have to somehow know it is there in the first place!
Obviously, I chose to hide mine behind a picture (hinge to the right, and powerful rare earth magnets placed on the safe hold it firmly closed (aligning with metal I inserted into the picture frame when the frame closes). I modified the shelves to better suit my needs, so their metal insert is gone, replaced by wood/felt inserts of my design.
There are MANY types, sizes, and versions of wall safes. Mine is a V-line. First photo is of mine, second one is from a sales site on the internet: