Most "gun" safes are pretty useless when it comes to keeping people out. The sides and back are usually made of 14 gauge mild steel - maybe 12 guage. With a sawzall and some decent blades a person can have a huge hole cut in them in 15 minutes. If they plan ahead a bring a circular saw with a good blade they could be done in a couple minutes.
Most have a B rating as a "residential security device" if they have a rating at all.
If you can get a B/C rating you'll have something.