If it was full auto it was more than just 'all pre-ban parts' - Your friend would do well not to advertise. It was a hell of a lot of fun to shoot, though, wasn't it?
Most individuals who built a rifle illegally (using pre-ban parts in a post ban receiver) did so out of ignorance. That's the ridiculous part about the Crime Bill. The rifles are identical in function (full auto excluded - that's Class 3 and a totally different crime) even though certain cosmetic features make one legal and the next illegal.
How silly it was to have to try to be the law abiding citizen in complete compliance with a law that essentially regulated insignificant features while the criminals didn't a) purchase with a background check,

honor the crime bill issues, and c) pay sales tax

I had to make sure the parts I was assembling didn't get me in trouble, and I took the time to do so.
BTW, no one was EVER convicted and sentence solely on a violation of the 1994 crime bill. Some folks had other charges trumped up due to using firearms that WERE in violation of the crime bill. Bubba at the gun range with his post ban lower and pre-ban upper with the bayonet lug is probably safe.... (as long as he doesn't flip the lever to full auto....)