[L33]

I apologise if this is the wrong thread to post this in, but if anyone could help with the problems below I'd really appreciate it!
Yesterday at a skirmish my WE M4 misfed/misfired right from the start. It would maybe fire one round, then start 'collecting' BBs and would spit 6 or so out at a time (even with the hop completely 'off') and would 'fire' 2 or 3 times on semi-auto. I tried various quality brands of BBs and the same happened with all of them, and it happened with all 6 of my magazines.

This is a v3 which has the NPAS kit (necessary to bring the FPS down to ~330 here in the UK), stinger hop kit and the 6.02 chrome barrel. I am running co2 if that makes any difference.

Thanks in advance for any help!


Edit: Update
I've stripped the gun and reassembled, cleaning it and looking for any obvious problems. I didn't spot anything, but the burst fire/jamming is still happening. A quick pull of the trigger on semi auto will fire 2 or 3 rounds, but only the first round will exit the barrel with any speed, the next ones will either roll out or fire out in a group.
This is definately not a case of too much silicone or any dirt in the barrel or chamber/part #117, I've thoroughly cleaned and inspected them!
Any help/ideas/suggestions much appreciated!