If the purpose of the paper is to act as a "jacket" that keeps the lead from touching the rifling and causing lead fouling, how is spin applied to the bullet? Does the paper have sufficient purchase to spin the lead? I know it must work, or no one would have done it then or still be doing it now. I have read about some who create a bullet that when patched is bore diameter, and most make it groove diameter (or somewhere between the two). I guess I can accept the groove-sized PPB, but how does the bore-sized PPB work if nothing is large enough to engage the rifling?