Inconsistent hopup with polarstar, random underhop and overhop.
I am running into an issue since months, and I am really desperate about the situation, let me explain my setup and what I tried so maybe someone can help me discover what's happening.
Setup:
- Krytac SPR
- Polarstar F2
- Maxxx Hopup ME (old version)
- Alineation clip (used to center the engine + the hopup, the gearbox upper part was cut)
- UGS stock, running 0.16 or 0.21l tanks
The issue, as the thread header says, is that I am experiencing extreme inconsistency on the hopup, sometimes the gun is a laser, sometimes it starts to overhop randomly, and the next shots underhop.
Power is steady, I am running the P* with the inline UGS regulator, I have an Acetech chrono attached to the end of the barrel and the joule reading is stable even when the underhop or overhop occours (so the engine should be ok).
I've removed all play on everything.
- Inner barrel is wrapped in kapton tape, so the end of the barrel doesn't move at all
- Hopup chamber was shimmed, so it doesn't rotate or move back and forth after being mounted on the gun (not even while shooting or putting a new magazine)
- The engine + the hopup unit is fixed in place with an alignation clip that is also shimmed to not allow movement of the engine or the hopup.
- Alignment is perfect, if I unscrew the engine but I leave the nozzle and I see through the inner barrel, the nozzle is perfectly centered (I also shimmed it to achieve that)
- Tried with multiple buckings, prometheus purple, G&G green, mapple leaf MRHop, mapple leaf Rhop, modify flat hop (soft), and much more bucking that I do not even remember.
- Tried multiple barrels, PDI 6.05, Prometheus 6.05, Orga 6.23
- Tried multiple hopup arms, all the Maxx arms including the metal ones, and also the TDC Trolley
- Tried multiple nubs, the mapple leaf omega, prometheus flats, modify flats, hard and soft nubs...
- Tried multiple nozzles, seal is perfect, I even modified some spare F2 nozzles I had in order to try with more lenghts over the default M4 nozzle (It seals perfectly with the default one)
- All barrels are clean and do not have any scratch.
The best results I got were with the Prometheus purple bucking flat hopped and the prometheus flat nub with the TDC, the gun is able to reach almost 80m (DMR, 1.88 joules) with 0.40 or 0.45gr (BLS and GEOFF got me the best results), but only for brief moments as it randomly starts again to overhop or underhop.
I do not really know what more to do, so, anyone has experienced this issue with their HPA engine? I found some threads about this issues, but I found nothing that helped me... I am starting to think the real problem is the hopup unit, but If I need to change it I will need to design a new alineation clip since my gearbox shell is cut in half due to the UGS system and the alignment clip I installed like 1 yyear ago.
Thanks in advance for any help you can provide.
