First off this things awsome!
I'm using the 1.5 carrier with 2 shims and the short spring. All together i fired about 1300-1400 rounds without one single break or chop! Usually the bolt would push the paintball either all the way into the chamber and fire or out of it and dry fire if it wasn't quite there. I can even stick my pinky in the breech and fire, just goes pff an resets.
The only problem i found was that when first gasing up the gun i had to push the bolt back about an 8th of an inch then it worked great.
This things amazing! usually i would have had atleast 2 chops and 1 barrel break, but not anymore!