If you really want to get into the nitty-gritty details of firearms, ballistics, the actual damage a bullet does, and proper firearms related nomenclature, check out Ben's blog and definitely pick up his book "The Writer's Guide to Weapons." There is no excuse for a writer to type the words "clicking the safety off his revolver" or "cocking the hammer on his Glock." If you don't understand why those faux-pas would cause many of your readers to close your book, then Ben's the man to call. He offers weapons-related technical advising services tailored specifically to fiction authors. I can't think of a better expert to call!