Air nozzle/Gearbox problem - M4

[makinitbig]

What I'm working with.
>4-5 year old D-boys M4 (used 7-8 times, tossed into a closet for a few years, new gearbox tossed in.)
>'AD Classic Front Wiring Complete V2 Gearbox' to replace the stock one.
>9.6v 1400mah Battery.
>Knight arms mid cap mags.
>Stock hop up, barrel, motor, ect.

What's wrong.
-Load mag.
-Fire one round to a mag fine.
-Four to five bb's eventually start jamming up the hop up.
-Air nozzle get's stuck back in semi, returns 30% of the time on full auto.
-Remove upper, exposing the air nozzle, still gets stuck.

What I've tried.
-Reshimming gears.
-Re-greased the whole gear box.
-Changed air nozzle, tappet plate, cylinder set (All stock d-boys stuff, problem persists, in different combinations.)
-Lighter spring.
-Several different batteries.
-Applied silicone oil to air nozzle as a last ditch effort.

Any suggestions? I've disassembled the gearbox 3-4 times so far, and am a little tired of looking at the guts of an airsoft gun

Thanks guys!

[ThunderCactus]

Does the nozzle move back and forth freely? Can you push it with your finger?

[Rabbit]

Just food for thought but try different mags - My brothers dboys had the exact same issue and frustrated me so much i wanted to punch my girlfriend out when she giggled at how frustrated I was getting.

Dboys has been known to make their receiver magwells 2mm bigger than standard ones (for example king arms) this caused the KING ARMS mags I was using (assuming you're using the same, not Knights Arms) to have all kinds of feeding problems and flucuation.

I had issues with genuine pmags, knock off pmags, and king arms mags when I tried them in the dboys

The issue was rectified when funny enough, Dboys brand mags were used.

Also check the trigger post inside of the mechbox, see if it snaped off - my brothers Dboys had its snap off in two games.

[makinitbig]

Originally Posted by ThunderCactus

Does the nozzle move back and forth freely? Can you push it with your finger?

When the air nozzle is fully forward it moves back and forth freely.

When it's stucks back it has a millimeter of play.

I should also mention when I'm firing full auto my piston will stop in random positions, most of the time short stroking.

Just food for thought but try different mags

Sorry I forgot to add that.

Tried several different mid-caps and different brands. Also two different hi-caps.

[Deadpool]

Originally Posted by makinitbig

When the air nozzle is fully forward it moves back and forth freely.

When it's stucks back it has a millimeter of play.

I should also mention when I'm firing full auto my piston will stop in random positions, most of the time short stroking.

Your nozzle is not installed correctly or broken. The tappet plate is not stuck in the groove of the nozzle of the groove is broken

And the full auto thing is normal, since the gearbox will stop at random places in the cycle after you let go of the trigger

[coach]

If when the nozzle stops fully forward and moves freely but springs forward when released, it's fine.

If you can push it back and it stays back, and you need to pull it forwards, it's busted or installed wrong.

A couple things to try if the nozzle is fine:
- turn the hopup completely off
- load fewer BB's into the mag