Were you actually intending to blow someone's head off? I'd rather have my money and stash taken than have some whack-job trying to annihilate my entire existence in every way possible (marriage, family, reputation, job and freedom)
Plus the child porn: He may not have shot it himself, but he sure drove up demand for it by acquiring those images, thus taking part in this disgusting racket.
I think 18 years is a fair, not even a particularly harsh sentence for what he did. He's also not a first-time offender either, if I remember correctly he got knocked for some other fraud before.