WE G39 NPAS fitting

[bumhulio]

Ok so after looking for ages for a fitting guide on the NPAS for the G39c and coming up blank, i thought i'd do trial and error. many people are stating that they cut the prongs on the rear of the bolt off and put a cross section in it to get the npas to work, i found that you only had to remove a small amount from nozzle in order to bring the fps down (no more then 1mm) i have two bolts and found that cutting down the prongs all the way makes the gun shoot at around 430 with the npas set to its lowest setting and when adjusted to its max setting, only raises to 450. on the second bolt i started by just taking half a mm and testing the gun would only spit out bb's. so i took another half a mm and now the gun shoots at around 260 fps on lowest setting and goes up to around 470 on the highest setting.
thought id share my experience with you in case any 1 else was having the same problem.
testing done with 0.2 gram bb's and asg green gas.

hope this helps.

[Panoptes]

Re: WE G39 NPAS fitting

I've just fitted mine and I'm getting shocking results.

Fully open: about 90 fps (with .25g)
Fully closed: about 160 fps

At least it's NI legal!

Everything seemed to go fine with the installation but what could be the problem? Which part exactly do I file down?

Also; any tips for holding the damn thing still while adjusting it?

[Barny Hamon]

Re: WE G39 NPAS fitting

IIRC Its similar to the WE M14 NPAS fitting, there are guides to fitting it on RA-Techs website.

It sounds like the NPAS is sitting too close to the forward edge of the nozzle, which would require filling down the plastic that the NPAS is sitting on by about 2mm So it sits further back. This is explained in the WE M14 tutorial.

As for holding it still whilst adjusting it ive done it before with a small screwdriver through the gas port in the nozzle to hold the main body of the NPAS still.

[Panoptes]

Re: WE G39 NPAS fitting

Cut the back part of the nozzle down by 1.82mm and still retain the shape? Are they serious?...

Better get me acouple o' spares.

[Barny Hamon]

Re: WE G39 NPAS fitting

Yeah i know its a bit of an ask, i managed it on 2 WE M14's. Used a dremel with cutting disk and a small file.

[Panoptes]

Re: WE G39 NPAS fitting

Looking at the G39 'back part', it looks as though I should only need to file down the two prongs by 1.82mm as the base of the NPAS appears to sit directly on them. It wouldn't make sense to file down both the cylinder and the prongs as I don't think that would change anything, mechanically. Would that be right?

Here's the M14 version but the G39 looks quite different:

[Barny Hamon]

Re: WE G39 NPAS fitting

Not entirely sure on the G36 as its been a while since i did one but i believe the space that the prongs make is integral to the design. So if you just cut the prongs down and the npas sat on the cylinder it wouldnt work correctly. So i think you'd need to recreate that space between the prongs and the cylinder by cutting into the cylinder.

[Panoptes]

Re: WE G39 NPAS fitting

Fair point I suppose. Anyone else concur or had different experiences/solutions?

[tisane]

On mine I cut the prongs by 2mm and the nozzle itself too.

It didn't look exactly the same as when I started but it did the job.

I have seen also that 2mm may not be enough, was walking another user through it a while back and he had to remove double that around 4mm.

To keep it still while adjusting just jam a small screwdriver in the through the inlet port of the nozzle and hold the cage part of the NPAS.

Start with 2mm and work from there.
I take it yours was one of the first imported G39s Pan?

[Panoptes]

Re: WE G39 NPAS fitting

Probably was an early one, yes. Ok, I'll try a 2mm profile cut. Sheesh...

[tisane]

Whoever said GBBs were easy....lol

[Panoptes]

Re: WE G39 NPAS fitting

Awesome, that did the trick. Thanks chaps. This thread should be stickied!

Do they tend to loosen/tighten and change fps as they're fired? I can't imagine they're very stable?

[tisane]

Nope as long as the NPAS isn't flapping around in the nozzle, ie the spring is holding it in place well enough, then the FPS should be stable, well as stable as it gets for a GBB.
It certainly won't adjust/deadjust itself.

[Skolob]

Re: WE G39 NPAS fitting

I just sanded the progs down to 1.9 mm in length which gave a good range and I cold set it at 320 but go from upper 200s to low 400s