I'm no expert at this but I believe that AI is simply straightning the case and increasing the shoulder angle so there should be no problem in using a factory barrel. However, if you are going to spend the cash on AI, you might think about purchasing a better barrel and having it chambered for the AI.
one other thing, if you are talking about a semi auto rifle, you should ask some people if they work w/ AI rounds without further adjustment. The straight case could lead to feeding problems. DPMS does offer a 300 SAUM in their AR rifles though.
I used to re-load but now I "hand-load".
-- Well, at least I try