High ROF AEG double feeding

[survivalkid1]

Hi all. Firstly, apologies for the username. I havent been on here for a fair few years!

Coming back to airsoft I have decided my CM16 that has been sat on the shelf for many years is due for an upgrade.

Upgrades so far -
shs high torque motor
shs 12:1 gears
sector delay chip
8mm bearings
shimming
element steel tooth piston
double o ring cylinder head
O ring air nozzle
basic mosfet

Problem- I was running a 9.6 nimh which the gun runs fine with but the aim is to upgrade to an 11.1 lipo. I tried one of my friends lipos and this is where I could see problems .

On single shot, the gearbox appears to do 1.5 cycles per trigger pull.

On full auto, which appears to be roughly 30 rps, every few shots I get a double feed of two low powered bb's and the accuracy of it all is terrible.

I have a few ideas with what might be wrong but I am unsure. I first thought that I was firing a bb before the other had left that barrel. After doing some maths I realise I was very wrong.

My next thought is that the tappet isn't returning fast enough and is pushing two bb's down the barrel before the air nozzle re engages.

The hop unit is all standard and the whole system operates fine at a lower rps but my aim is to be running with a high rps on an 11.1v.

I plan to put an ab mosfet on which should deal with the 1.5 semi cycles but I'm lost with the double feeding. Everywhere I look says the hop is the issue but the only variable in this is the battery and thus the rate of fire.

thanks in advance
Ethan