I have a box of gun locks. I put one on a gun once but then couldn't find the key when I wanted to take it off the gun. Could you imagine what would happen if you had a gun lock on a gun and a bad guy came in your house?
Gun locks are pretty handy for gates, sheds, bicycles, etc. The only gun lock I have that isn't useful at all is one that is designed to fit exactly into the trigger guard of a specific gun. I can't lock a box or shed with it.
I'd like to build a vault into my next house but I may be too old for a next house.