Very low FPS issue - now solved

[colinjallen]

 I have been messing around with an old G&G CM16 Carbine (the original version) and am getting around 180FPS.  

I am very experienced at upgrading, fixing and building AEGs but cannot work out what is wrong with this one.

The gearbox is original with the following exceptions:

SHS M90 spring
Metal ball bearing spring guide
SHS cylinder head
SHS O ring nozzle
Gate PicoSSR3 mosfet
Rocket high torque motor

There is no delayer on the sector gear.

The airseal is pretty much perfect and everything runs as it should.

The barrel is the original aluminium piece of crap.

The two hop setups that I have tried it with are:

1. ZCI plastic hop unit; Maple Leaf Macaron and Omega nub

2. Original G&G hop unit; G&G Green hop rubber and nub

Both give the same FPS.

With the nozzle fully forward, there is no light leakage down the barrel when an LED is shoved up the feed tube, so I am certain that the nozzle is engaging correctly with the hop rubber.

The paper test on the feed tube shows nothing.

Any ideas?

 

[Groot]

Start with the obvious. 

Put a new spring in and rule that out. 

If it's an old gun, there is a chance the spring has spent a long amount of time compressed. 

 

 

[colinjallen]

Start with the obvious. 

Put a new spring in and rule that out. 

If it's an old gun, there is a chance the spring has spent a long amount of time compressed. 

 

The spring is new.  This evening, it has had an M90 and an M100 in it.

 

[colinjallen]

Problem now resolved.

 

[SSPKali]

Problem now resolved.

So what was it? Just in case someone else runs into the same issue!

 

[Rogerborg]

I also need closure on this anecdote!  Sounds like the obvious stuff had already been ruled out.

 

[Lozart]

I also need closure on this anecdote!  Sound like the obvious stuff had already been ruled out.

I'm going to guess that he's keeping schtum because it was something really stupid.

 

[Groot]

@colinjallen Come on man, put us out of our misery 

View attachment 77977

 

[DerDer]

Was the cylinder the wrong way round? 

 

[ak2m4]

Such a little tease ?  Did the new ZCI barrel fix the problem?

 

[colinjallen]

Such a little tease ?  Did the new ZCI barrel fix the problem?

No, that was for another gun that needs to be brought back to life.

Apologies all; I have been walking and wild camping on Dartmoor since that last post and have not had access online.

I have no idea what the issue was; I stripped the gearbox and ZCI hop down again, checked everything, reassembled it and, whizzo!  320FPS!

Dartmoor was fun; we found a rather large tag round.

View attachment 78116

 

[Rogerborg]

No, that was for another gun that needs to be brought back to life.

Don't care.

Apologies all; I have been walking and wild camping on Dartmoor since that last post and have not had access

online.

Don't care.

I have no idea what the issue was; I stripped the gearbox and ZCI hop down again, checked everything, reassembled it and, whizzo!  320FPS!

Cool story, bro.

Dartmoor was fun; we found a rather large tag round.

Don't care.

Great to hear that it sorted itself, cool story, and so on, and so forth.

 

[colinjallen]

Don't care.

Don't care.

Cool story, bro.

Don't care.

Great to hear that it sorted itself, cool story, and so on, and so forth.

View attachment 78125