[dpvu]

How are you checking compression? Try taking everything except the cylinder, piston, tappet and nozzle out of half your mechbox. Pull the cylinder back, hold the nozzle forward and the cylinder in place with one hand. Seal the nozzle with your finger and then try and push the piston forward. It should be very difficult to do. Do it with the piston all the way back, in the middle and near the end.