You're having the same problem I had.. Try taking the stock of the gun off. Then try cocking the gun and see if its easier. For some reason, when I would tighten the two bolts to secure the stock it seems that it pulls the front of the gun down which causes somewhat of a kink between the bolt and the hopup. The way I fixed it is I would put the stock back on and slightly tighten the bolts until it would start. Then I would get some faom and put it under the barrel acting like a spacer in a sense, and that would help.. A little.. Also, with the stock connected, try pulling the bolt back, flip the gun over and look into the mag catch. You should be able to see the two adjustment screws for the pdi hopup. See if you cylinder head is rubbing on one of the bolts.. If so, problem solved.. Good luck..