Although I don't know the specifics of your situation, my suggestion is to get a proper fire rated gun safe. If you can't at least afford the basic model that has a fire rating, start working overtime! Seriously, I'm amazed when people have hundreds or thousands of dollars in guns, ammo, and accessories, and then buy a cheap sheet metal non-fire rated cabinet. You can get fairly compact safes that you can hide (sort of) We have a Liberty 24 safe that weighs 875# empty and stands about 5' tall. I had to put plants on it just to make it disappear
Anyhoo, whatever you can afford, make sure it's fire rated, and get a Goldenrod dehumidifier for it. Also, BOLT IT DOWN!!! And whatever the gun capacity says,
DON'T BELIEVE IT!!!
You will fill it up in no time. Good Luck.