Gearbox working but not shooting?

[Jags87]

OK so my CA M15 A4 is not shooting the bb's. All the gears are turning the motor works the bb's feed but they just roll out the barrel. The hop up also seems to jump around a bit while firing the weapon. So with my lack of knowledge i come to you guys. Any ideas and solutions just pm me or reply to this post. Thanks.

[Whiskey11]

I've had this happen before, it happened because the piston head broke off from the piston and turned around inside the cylinder, I'm lucky I didnt bork up my piston.  Re check all your compression parts.  Do you have the spring that pushes the hop up unit torwards the gearbox?  If not that could be another problem.  Lastly is the hop up applied too much?

[Jags87]

yea the spring is still there for the hop up. when i took it out though it look a bit bent outta shape. How long you think it would take to change out the piston head? The hop up just seems to move around and before the piston went out the mad seemed to move around a little bit while firing also. thanks for your help

[Jags87]

anyone else have a take on this topic?

[BATMAN]

Jags, how confident are you with taking apart your gun?  That's probably what you're going to have to do.  This is what would cause a gun to not feed:
1. Magazine not functioning correctly
2. Broken hop-up/feeding nozzle
3. Hop-up rubber not seated correctly
3. Broken air nozzle
4. Complete loss of air seal (such as a loose or broken piston head)

If BB's are falling out of the barrel even when not attempting to fire the gun, then it's likely hop-up related.  If that's not the case, then you're going to have to open the gearbox.  If you don't feel confident doing that, then have someone look at it for you.  Hope that helps.
-BATMAN

[Jags87]

not to confident the last time i tried my gearbox went flying in 30 different directions. I dont know exactly how to appraoch it casue iam not sure where to put the shims and bearings at if it all comes apart again. I know the shims all have different measurements and they al have there specific spots or the gears wont work right. Thats what happened last time.

[BATMAN]

Well, if you're anywhere near Tempe, bring it by Gearbox Airsoft, and I'll take a look at it for you.  Usually I can tell what the problem is without even having to open the gun; that way you'll have an idea of what needs to be done.
-BATMAN

[Jags87]

well the gun is all apart the gearbox is out but i can put it back together before i bring it