This is really exciting -- the use of off-the-shelf parts means that just about anybody could build one. I've got three questions:
1. Why did you use shells? Is it just to avoid problems with the clip, or does the "bolt" cycle so fast that it would rip up stefans?
2. Did you have to machine any of the parts? The "receiver" into which the barrel fits looks like it might be custom-made.
3. Where can I order the parts?