Hello, I have recently joined the MWS club and bought the M4A1 and the MK18. The M4 have just few mags shot and I have a serious issue with the MK18, just after 8 mags. After finishing the 8th mag on full auto, the bolt failed to return fully, looks like the nozzle tip hit the hop chamber and get deformed slightly. Ever since then, the gun gets jammed after few shots. I am using green gas and 0,25 guarder BBs. After that I tried also the high polished bio BBs, same story. I am very surprised, been using GBB from Marui for ages and never had any issues….. I am looking for a replacement nozzle but mainly the dynamic precission ones are available. Are they any good ? Below a pic of my badboys: