Years ago, I threw one together on a stripped, transferable PAWS lower. All the other parts came from Quality Parts, which evolved into Bushmaster. I used what they called their 10" "machine gun" barrel and the standard birdcage flash hider. Absolutely no problem with the gun running. Well, the first bolt group didn't do so hot, but they immediately replaced it. I've had to replace a broken extractor and a few gas rings, but other than that, the gun still runs as good as ever. I do have to keep the bolt oiled and after 200 rounds, spray it again to keep it from jamming. Maybe I just got lucky. At that time, I was mad because the lowers jumped form $200 to $400 back in '86.