Hopup/magazine/who on Earth knows problem - M16 variant

[BATMAN]

I've tried different bb's.
The first half of the bag was fine. THEN the problems started occurring somewhat suddenly. I've used G&G, TSD, and Goldenball in multiple weight from multiple bags. Same results... so unless my barrel suddenly decided to be less than a 5.95... but yeah, that's one of the things I plan on checking. Just in case.

Seriously, rule out the easy stuff before you start replacing every part in your gearbox.  Bore issues or not, there could still be a problem with your barrel, or even the hop-up.  They take seconds to switch out; it's worth the time.
-BATMAN

[axisofoil]

Earlier in the thread, that's one of the things I said I was going to check.

[Shadow]

I had this exact issue last week.  Turned out to be a very small tear in the bucking where the nub is seated.  Tear was enough to cause the bucking to double back on itself when a bb passed under it, causing jams.

[axisofoil]

Well, after removing/replacing the barrel, bucking, hopup assembly, nozzle, tappet plate, with different ones one piece at a time, I discovered when the problem seemed to come and go instead of just assuming it's random.

The problem only happens with mags that are either full or near full. Since I only use midcaps, the force with which the spring pushes the bb's is stronger when the mag is more full. Based on this, and noticing that my gun is unable to push a bb through a prometheus hard bucking and into the barrel, I believe that the tappet plate spring is worn out.

And... one thing the sector clip does, is keep that spring stretched out while the gun is in rest mode. I doubt if that made much of a difference beyond the part where that spring has had a long tough life. It's a little past 200k rounds or so.

[MLA PRO]

This all helps me with a problem ive been having. The same thing has been happening to me, but  it turned out that my cylinder head cracked a bit. My gun fired agian, 2 hicaps worth, and then the same thing happened. Now my piston head broke. Im getting a shipment of parts sometime this week, hopefully ill get it to work again. But ill also try what you guys suggested.