Problem with m4 on semi

[Mongrol]

I'm putting an m4 together and have all the parts I need and have it assembled, plugged in the battery and had a problem, on semi auto the trigger clicks ( audible click) and the motor tries to turn but no shot (like having a dead battery) but as soon as I switch back to full auto it works fine, switch back to semi, same problem. Any suggestions?

[Patrick750]

that happened to me, i took it to AONW and it ended up being a tappet plate problem. And are you building your m4 by scratch or what?

[Mongrol]

Yes and no, it was from a base gun but almost everything has been swapped out, gears piston spring spring guide cylinder cylinder head air nozzle motor and tappet plate. All the originals of those have been swapped out