Here's an extraction from one of the Dan Theodore Tech articles:
Visualize if you will a PP'ed bullet exiting the muzzle. At the instant the bullet base clears the crown, all of the paper-patch should be completely off the bullet. If it is not, a flyer is likely to occur. Quite a bit of discussion was undertaken by some of The Cup marksmen, paper-patch and grease-grooved users alike, concerning why the paper was not coming off some bullets in a consistent manner. It would seem, to the casual observer, that the high speed air moving over the bullet from its forward motion would rip the paper off the bullet upon its exit from the muzzle. My current thinking is that when bullets spin at high rotational speeds and are moving forward at high speeds non-intuitive things happen to the paper-patch, caused by the airflow around and over the bullets as they start their journey down range. A 45-cal bullet exiting the muzzle at 1,350 fps is spinning at 54,000 rpm when launched with an 18-twist barrel. That high rate of spin drags air around the bullet due to surface friction. The airflow from the bullet flying down-range streams over the air dragged around the bullet due to its high-speed rotation. The interaction between these two air flows might act to hold the patch on longer than one would intuitively think if it is not appropriately torn and/or cut as it exits the muzzle. When the paper-patch does not instantly depart the bullet upon its exit from the muzzle, aerodynamic drag must increase and thereby slow the bullet more than usual, which in turn causes the bullet's short impacts.
Note
What I'm wondering is if anyone has ever thought about using something akin to an Exacto blade to make four concentric cuts through the patch paper down to the exterior of the bullet shank on a loaded round back to the case mouth to see the results thereof on the target??