Originally Posted by ujiro
Mine does that, only because I use a very powerful battery, so it always over-turns a bit every time. You could possibly remedy this by using a sector clip.
A sector gear clip doesn't actually help that problem, it only helps the nozzle timing. To cure that over turning thing, just lightly tap the trigger on semi to pull back the piston, then pull the trigger again, and what you want to hear is just a click as the piston is released, then it's fully decompressed as the gears didn't have any momentum to carry the piston another half cycle.
Also, there are 2 parts where the nozzle is fully forward and the first shot will be a dry fire. The first part is at a half cycle, the second part is right at spring decompression. If the gun doesn't have a mosfet there may be a small chance that the sector gear stops right after spring decompression and the tappet is fully forward. This is pretty rare though as gear momentum usually pulls the tappet back.
It could happen on full auto however, which is why you dry fire a few times after mag removal.