Stick with a brand you know and respect for their film cameras. And be sure it's one that in addition to having some kind of closeup or macro setting, has a fast lens (like at least f2.8) and can produce good results with higher ISO (use to be called ASA) settings. Flash photography just doesn't work well with the metal surfaces of a firearm.
It's my understanding that all the well known camera brands have made both good models and a few real clunkers. Here's the URL of a website that does very thorough reviews of digital cameras in most price ranges by most well know brands.
http://www.dpreview.com/