Follow up, im getting two firing pins machined this week... mine bent after a run in with a faulty fire controll group (full auto sure was cool though). The disconector was disconecting... bad disconector. The old fire controll group has since been destroyed and a new one is in the mail from bushmaster. The fire controll group is exactly the same as an AR15s.
The rifle is pretty cool, but the spare parts are lacking. It uses an AR-15 trigger group, cam, cotter pin, extractor, extractor spring, front pivot detent, front push pin, and a couple of other parts.
The rifle is very robust, and is ingeniously put together, the piston sits in a little cup on the bolt, and is not permanantly attached to it. Its pretty heavy too... I cant wait till mine is running again.
Even though I had a bad first experience with it, I found the problem and have since fixed it. The fire controll group released the hammer before the gun cycled and would catch the firing pin and bent it. Im just waiting for my new firing pins before I get it going again.
Cost: 60 bucks for two firing pins at local gunsmiths shop.