DIY: Gun Safe
I have a tall, five drawer filing cabinet that I could see being refit like this.
As I was looking at mine I might have seen a design flaw. If you make these mods and fill it up with long guns, then slide open the drawer, it could tip.
The advantage of the file cabinet normally is that you open only one drawer at a time.
To make this work you would really need to bolt the whole thing to the floor or the wall behind.
I can't say that this would even be good hidden storage. Burglars would still open it. This lock would slow them down but not stop them.
--This would be useful for keeping your kids out.