Feeding problem on jm8 m4

I was helping a buddy do the once-over on his new jm8 blaster (green o ring, brass jm8/9 cylinder head and nozzle), so we actually have compression in the cylinder now. But there is a brand new problem in that he can fire 4-5 shots before the blaster jams up and he has to cycle the mag to clear the jam. He’s running gold milky’s through a fighting bros tight bore barrel and it’s a 1.25 spring if that has any effect on it.
My theory is that the nozzle isn’t retracting far enough, but I’m not certain how to fix that except for a sector delay.

Who’s had a similar problem, and how’d you fix it?

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Seems to be all to common with tight bore barrels as its been brought up a few times. 1 are u doing controlled growth gels need to be about 6.8 to 7mm for those barrels. 2 try a delayer chip it didn’t work for me but u never know u could be lucky

There are a few things that can cause feeding issues.

  1. Nozzle not traveling back far enough- delayer chip will help
  2. Gel ball to small for the mag to feed reliably- issue is from using a tight bore barrel.
  3. Piston head causing suction on the return stroke - check o ring or hole size in piston head
  4. Poor quality t piece

That’s a pretty good reference to start with, cheers. The gels were firing reliably before fixing up the air seal, so I’m going with the delay chip firstly