This video will teach you how to make AA guns.http://http://www.youtube.com/watch?v=DaTN5sSqIX0&list=UUYFQpHGsOdi2_83b7E6-gIA&index=4&feature=plcp
I'm not going to lie, this video was really hard to take seriously. You need to work on your commentary, and learn to use edit coordinates.
The AA guns are pretty interesting but i do have to agree with FrozenGoathead about the commentary because it is a little weak and could use some work.