I am looking for a safe for my third floor apartment. I am looking for something large enough to hold my shotgun and another couple long guns. Also, i have two handguns and intend to add a few more to the collection. I would like it to be as strong as possible. I have sentry safe that would be enough for papers and such. This is just for guns.

Whats the best I can do with about $400? I need to fit it in a closet so the more compact the better.