Extremely innacurate GBB

[Big Jilm]

I've got a HPA'd WE M4 with a Lambda 6.03mm barrel and maple leaf bucking, and im getting grouping at 15m that could be measured in feet instead of inches.. I seem to get a couple shots that are relatively consistent and on-target, then some insane flyers that go left, down, up and right, in other words inscredibly inconsistent.

I'm a bit lost on what to do, the barrel is brand new and clean, and I've tried both a maple leaf and 4uantum bucking/nub. Only thing I can think of is that I have an NPAS that I put a small dab of glue on the threads to stop it from unscrewing but how could this be affecting my accuracy?

Any help would be appreciated!

 

[Enid_Puceflange]

Hello and welcome.

Firstly, what fps are you getting?
What weight bb are you testing with?

 

[PiratesARRus]

One thing worth trying is adjusting the npas as they can do some magical things at the edges of their range that even a quarter turn can fix.

Also worth checking if the inner barrel has any wobble to it if you haven’t already but I wouldn’t expect that to be the issue if your at least getting some consistent shots.

 

[Tackle]

I don't know about gbbr or hpa, but I agree on checking the npas, which to my understanding is a power adjustment valve ?, as power fluctuations would have the effect your describing.
If you've got a chrono, maybe consider taking some readings before touching the npas, see if there's any consistency in the output power.

 

[Big Jilm]

Hello and welcome.

Firstly, what fps are you getting?
What weight bb are you testing with?

Click to shrink...

Thanks, I'm using .30g Geoff BBs and getting between 1 - 1.1J last time I tested. I'm going to try with some 0.28g BBs I have to see if the issue is the ammo but I know Geoff's have a good rep so doubt they are the issue

 

[Big Jilm]

One thing worth trying is adjusting the npas as they can do some magical things at the edges of their range that even a quarter turn can fix.

Also worth checking if the inner barrel has any wobble to it if you haven’t already but I wouldn’t expect that to be the issue if your at least getting some consistent shots.

Click to shrink...

Well it is almost maxxed out to be fair, issue is I've epoxied it closed

 

[StoveCap]

To my understanding HPA'd GBBs should use the pressure regulation to adjust power not NPAS'es, If you have a spare BCG or nozzle I'd try with those but if not the first thing I'd try is the stock rocket valve. If that fixes it then you know its the NPAS. Apart from that perhaps you've reassembled the hop up wrong in some way?


Only other question I'd ask to diagnose is did the gun produce the same inconsistency when stock?

 

[MistakenMexican]

Well it is almost maxxed out to be fair, issue is I've epoxied it closed

Click to shrink...

Replace the NPAS with a normal floating valve for a WE GBBR and that will fix a lot of your problem straight away.

NPAS’s are notoriously unreliable at the very extremes of the adjustment. And if you’re using HPA, you don’t need an NPAS anyway.

 

[Adolf Hamster]

To my understanding HPA'd GBBs should use the pressure regulation to adjust power not NPAS'es

Click to shrink...

It'll be situational.

If you've got a low limit then dialling the feed pressure low enough to meet the energy output will mean you've got too little pressure to cycle the action properly.

You get the same issue even with the solenoid engines which is why low flow poppets are a thing to let you run a reasonable pressure for cycling without the gun being too spicy.

That said, in this case it seems like shimming a static rocket valve to the ballpark of your desired energy then using the reg to fine-tune energy would be better than trying to use an npas.

Edit: also worth looking at the bucking, if its the type with the metal c clip try removing that. I have found that can make for too tight a clamp around the nozzle meaning it'll sit slightly out of battery. This means the seal between the mag vent and the nozzle is insufficiently tight and some combination of those features will give an air leak and resultant inconsistency.

I also have a memory that the we buckings are a touch longer than standard ml, you'll be able to see that if its sitting a bit short in the hop chamber which can give the same poor air seal issues.