There's been some debate about that. After John Hagan's suicide in 24 10-7, Calleigh couldn't work in the firearms lab anymore, but she then came back in that scene from "Shattered". Case in point about sloppy writing and lack of accuracy--There was that scene in "Down to the Wire" that really bugged me. She's supposedly testing a firearm when Rick Stetler comes into the doorway to inform her that he's pulled her off the case. Take a good look. -Neither Calleigh nor Rick are wearing hearing/eye protection. -Door to the ballistics lab is open, letting the sound travel. -Calleigh's hair is hanging around her face. If that firearm recoils, her hair could get caught in something, compromising evidence, and it's downright painful to say the least! Major, MAJOR OSHA violations right there, and as IAB, Rick himself should have been wearing hearing/eye protection and shutting her down for not doing the same. But hey, I guess somebody thought it looked darned sexy. To be honest, MANY of the older characters don't seem to do what they used to anymore. For the longest time, H wasn't in the lab at all. In the early years, Calleigh and Horatio had special skills, but nobody seems to do that anymore.