Thanks man, if it helps just one i'm happy. My findings so far are pretty simple. I feel you can use a 209 primer if you don't exceed 100grns by volume of powder and a 250grn bullet.

The 300grn bullets and heavier are creating in consistent results. Over the next couple weeks i hope to figure out a safe powder range and heavy bullet for a 209 primer in a plunger gun.

Though i have found and advantage with Knights using the red plastic jacket. The primer does not come apart and the jacket comes out pretty safely so far. I'm hoping to video my finding this month if possible.