What needs modification on HPA drop ins?

Hey all,

Looking into HPA drop in systems Polstar etc, what needs modification?

Does anyone have experience? documented anything?


This is the way :ok_hand:


The mystery for me is how the gels are fed, mag motor actuated, etc.

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I read up on that when I looked to earlier in the year.

Trigger is still electric so, essentially the same deal as now

At least on the one I want…think it was the F2

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I was thinking about it but was wondering about the travel length for the nozzle being an issue etc…

might get lucky and there might be a nozzle that fits for the polarstar Jack:

“recommended nozzle length may calculated by measuring your original gearbox and applying the following formula: TIP = F + B - (A/2) - .0875. A more precise measurement (which accounts for the hopup and bucking in use) may be obtained by installing a nozzle into the system which is slightly too long for the replica and measuring the nozzle setback when placed into the hopup.”

Nozzles can be found here http://archived.polarstarairsoft.com/prod-jack.php?sort=num&sd=desc#

I’m guessing that’s the “secret sauce” the elite builders are talking about.

Yeah i guess so, when i get time i’m going to take measurements from a mk v2 using fb/warinterest nozzles, hopefully there is already a compatible nozzle

added image for reference

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Found out on how to add mag terminal wiring. You just can email polarstar on how to do it, they will tech you as they teach i am. Finally my question have been answered lol.


It’s not the length of the nozzle that is the problem, it’s the travel.
Two totally different things.

That above is saying for example that if the nozzle is 2mm too long, set it back 2mm

The issue is the distance it travels.
That’s why aîrsoft gearboxes don’t always work well in a blaster. The nozzle does not travel back far enough to let a 7.5mm gel past.
And if you move the nozzle start position back 1mm, then it won’t travel forward enough to seal the tpiece.

You can change the dwell timing on HPA, The dwel is how long the nozzle stays in the open (back) position. This might help it stay open long enough for a gel to get from the magazine into the tpiece, but the nozzle still needs to go back far enough for the gel to get past.

That’s what the tappet takes care of in the AEG gearbox. But no matter what the timing is,
It still needs to move far enough.

If I open a door 3 inches, you still can’t get through. Even if I hold it open longer for you :grin:
And moving the door back a few feet won’t help either if the wall and door frame moves back a few feet with the door.

Clear as mud? :rofl:


AS Bucking won’t work with gels, so forget that.

Still need a FCU to power the mag and maybe the trigger depending on model you get. PS Kythera is mechanical trigger. Spring loaded mag won’t work so well due to gels being soft so will still need some power.

As for the nozzle travel, no idea, you suckers get one and let us know. Thanks :rofl: :rofl: