I've had paint that was so bad, that I couldn't fire a shot out my barrel without it breaking, even with the level 10. That was with a properly sized barrel. With experience, I have come to overbore all my barrels and don't have that issue any more. Good paint benefits from a proper bore match. Overboring, doesn't hurt the accuracy that much but does affect the efficiency a bit. The upside is that it really helps prevent busted balls when you have really brittle paint.
The level 10 bolt only prevents chops in the first 1/4 inch of the bolt movement. The bolt would need to be at the back of the breach for a ball to be partially loaded which is a situation that would cause it to be chopped. The bolt would be very gentle when it made contact with the ball in that location. Once it gets past the 1/4 inch point, the bolt is subject to full forward force. If the barrel offers too much resistance due to an oversize ball, or a barrel is too tight for the paint, then the force of the bolt will smash it into the opening causing some of the paint to squirt back onto the bolt and up into the breach. This can happen even if the paint barely touches the barrel walls, if the seams are extremely weak. Its something that should be looked at.
Normally, a level 10 bolt will prevent all chops, even if you use the shortest gold spring. The air source doesn't matter. The force on the bolt is held constant by the regulated air set by the velocity adjuster. If the first shot in a string is busting, then that is an indication that you are not experiencing a chop, but rather a barrel break.
Except for the Automag in front, its usually the man behind the equipment that counts.