G&P M4 possible piston issue

[Reaperman]

Afternoon,

After chronoing my gun at the last meet the bloke said my piston/nozzle might not be resetting enough/every time. I've mucked about with it quite a lot since and sure enough I can still see the nozzle through the hop in the magwell sometimes.

Is this normal? If not what effect does it have and should I do anything about it?

FPS is a *little* less than expected for the model but still works well (assuming I can finally sort the b*****d hop up!).

[Vex]

Re: G&P M4 possible piston issue

What have you mucked about with?

You should be able to see the piston from inside the mag well, that is how it feeds bb's. When was the last time you cleaned your barrel?

[Reaperman]

Re: G&P M4 possible piston issue

What have you mucked about with?

You should be able to see the piston from inside the mag well, that is how it feeds bb's. When was the last time you cleaned your barrel?

Heh, that's awesome

Apologies wasn't clear - I can see the nozzle some of the time and not others, it doesn't seem to do a complete cycle.

Nothing related to that, changed hop unit, nub, bucking etc. all front end stuff really and yep, cleaned the barrel a couple of times lately.

[RitchieTheBrit]

Re: G&P M4 possible piston issue

My gearbox rarely settles correctly after a burst. On semi, it usually settles in the open position (the start of the cycle, nozzle pulled back, no tension on piston spring).

As long as the nozzle travels all the way forward when released, you're golden. Maybe a worn bucking, or you have air leak around the nozzle. A cheap upgrade is a new nozzle with an oring.

[Reaperman]

Re: G&P M4 possible piston issue

My gearbox rarely settles correctly after a burst. On semi, it usually settles in the open position (the start of the cycle, nozzle pulled back, no tension on piston spring).

As long as the nozzle travels all the way forward when released, you're golden. Maybe a worn bucking, or you have air leak around the nozzle. A cheap upgrade is a new nozzle with an oring.

Ok cool, thanks that's useful info.

I was thinking about getting a plastic nozzle with O ring, G&P metal one at the min isn't supposed to be the best air seal... are they easy to swap out?

[RitchieTheBrit]

Re: G&P M4 possible piston issue

Unfortunately, it's a gearbox strip. Your tappet plate lives inside the gearbox, with the end protruding out and holding the nozzle. This is what pulls the nozzle back and forth, driven by the gears inside. It's not a hard task, but it requires patience. There's plenty of YouTube videos showing how to strip a v2 gearbox. Watch them, and see what you think.