the weight is needed to delay the bolt is my understanding. I'm using the piston to add the weight and to veary the weight as needed. the hard part now is figgering out the angel for the feed ramp. I do not have a 9mm hand gun to eye ball. I think my ramp on my .45 should work.
A milled reciver would be a real good start. I just needed a progect child (read cheep). muttman