I'm shooting pump this year and have been using my Illusion with great success/enjoyment.
I am however wondering about the ballstops - every time I pump and wait I have paint rolling out the barrel - making me either recock, or shoot an air biscuit in the place of a shot that could have changed the game.
I've noticed this is due to the placement of the ballstops - they work great until you return the pump to the front position which returns the bolt and pushes the paint right past the ballstops out into the open chamber.
Kinda weird to leave the pump pumped and return it to the front position before I shoot. Has this changed your playing style when using the illusion?
I've found that finding the proper barrel size is a great advantage. Been a while since I've played, but my J&J barrel kit would allow me to size my barrel bore to my paint and prevent the problem you describe.
I'm sure the OP already figured this out months ago, but the ball detents only prevent double-feeds- once you chamber the ball the bolt pushes it past the detents and the only thing keeping it from rolling out is a good fit with the barrel. Fortunately, the Illusion is cocker-threaded, so finding a good tightbore barrel like a Lurker Eigenbarrel is very easy.
I've got my own question though- does anyone know what pressure the stock Illusion likes to run at? I'm considering slapping a regulator on mine.