While I am not an "expert" per se, I did a lot of research before buying my last safe.
I get disappointed when I see people buying cheap, bargain basement "lockers" that are poor excuses for secure gun storage.
You need to look at specs, if the manufacturer does not list the insulating material or the actual thickness of the steel used in the sides, back and top, it is because they do not want you to know.
Many of the safes sold at places like Walmart, Home Depot and Costco are simply "residential storage containers" and do not qualify as secure or fire resistant.
I did a write up on my blog that includes pictures, descriptions and links, this helps the buyer make an informed decision.
BTW I do not work for a safe company, nor do I sell for them.
My first safe was a Liberty Franklin series 35CF, my first mistake was buying a Liberty, my second was buying too small!
The next safe I bought is a Superior Master Series 50CF, I made the same mistake in that it is too small.
Read more here on my blog: http://tincanbandit.blogspot.com/2013/07/a-primer-on-gun-safes.html