Pull that slide back and let'er rip. If it is a 9mm, it won't hurt anyone anyway! :D
I think that right now, our character's firearms experience will be limited (save for those with a history with guns), so detail would be nice, but as the story progresses and everyone becomes hardened zombie killers, minor details can be cut, replaced with more broad information. Personally, I'm going to attempt to follow this since my character has never fired a gun, but slowly he'll become more accustomed to them. I mean, it
is California, so guns are hard to come by.