I noticed that on semi the nozzle's resting position is random, all depending on how fast the gears slow down after firing.
You have Overspin.
Overspin - AEG's were engineered to be operated with batteries with discharge rates of 10-15 amps. Most batteries with high discharge rates of 30-35 amps or greater have the power to compress big springs and increase rate-of-fire. Unfortunately, a side effect is Overspin. Overspin occurs when the flow of electrons is cut from the trigger, but the residual electrons continue to spin the motor due to the high discharge rate and torque of the motor. This leaves the piston in a random position of being "half cocked", and the nozzle sometimes retracted. On Thompson V6 boxes, semi-auto results in 2 and even 3 round bursts. To end the effects of Overspin, a MOSFET trigger with ACTIVE BRAKING is installed. The braking will immediately cease the flow of electrons by sending the residual electrons to the negative side of the battery. This can aslo be accomplished with a SPDT auto relay. Which is much too large to install into most AEG's.
Is Overspin harmful? Not really. Unless you have a very weak spring and the piston is 3/4 of the way back.
Is there another way to stop overspin besides a MOSFET or SPDT relay? Yes. Downgrade your battery. Or get a low torque motor.
What's a low torque motor? Spin the pinion head of your motor. The easier it is to spin the pinion head, the lower the torque. You can also tell by the magnetic field generated by the motor.
Feed:
As others have stated the Tappet plate retracts the nozzle. If the cam on the sector gear has worn the tappet plate plastic, it will not fully retract stopping a bb from entering the hopup chamber.
Also check:
1. The hopup and bucking. Turn it off and test fire it.
2. Try another magazine other than a hicap.
3. The Magazine fit. Rock the mag in the magwell when test firing. Rock forward, fire. Rock back, fire. If possible try another magazine brand. Not all mags are 100% compatible.
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