If the level 10 is actually stopping on the ball and venting air, then the level 10 is working. You won't need to add anymore shims. If it won't reset properly, or if the reset is slow, then something is too tight. That could be the level 10 carrier or something else. Its usually the level 10 carrier. Usually it will fire and return with the short spring if it is close to being a proper fit, but may hang up on the return if the carrier is too tight and you have experienced an antichop action.
As mentioned above, make sure the balls do flow through the breach when you take out the detents. Another thing to check is the fit of the bolt in the breach. Try dropping the bolt into the breach from the back of the gun to see if it slides easily without any restrictions. Make sure there are no burrs on the inner washer separating the front half of the body from the back half. Sometime they can get mushroomed and cause some rubbing.
Except for the Automag in front, its usually the man behind the equipment that counts.