PP stands for Paper Patch, not plastic patch.
Paper patching was done by many target shooters starting in the mid 1800's.
These very thin paper patches were used on elongated bullets, something else that only target shooters were shooting back then.
Several different methods were used with paper patches.
One of the more common ones was to use a false muzzle on the end of the guns barrel. The paper was cut into narrow strips and placed across the face of the false muzzle.
The elongated bullet was then rammed down thru the muzzle, taking the paper with it.
Another common method was to wrap the bullets with two turns (or more) of paper which was then twisted at the base of the bullet.
The paper was then wetted and when it drys it shrinks to create a tight fitting sleeve.
That sort of PP bullet is shown below. I shoot these in a .40 caliber muzzleloading Schuetzen rifle.
Paper patching was done by many target shooters starting in the mid 1800's.
These very thin paper patches were used on elongated bullets, something else that only target shooters were shooting back then.
Several different methods were used with paper patches.
One of the more common ones was to use a false muzzle on the end of the guns barrel. The paper was cut into narrow strips and placed across the face of the false muzzle.
The elongated bullet was then rammed down thru the muzzle, taking the paper with it.
Another common method was to wrap the bullets with two turns (or more) of paper which was then twisted at the base of the bullet.
The paper was then wetted and when it drys it shrinks to create a tight fitting sleeve.
That sort of PP bullet is shown below. I shoot these in a .40 caliber muzzleloading Schuetzen rifle.