HPA m27 inconsistent groupings.
I have been having consistency issues with my m27 and am looking for a tech to work on it.
Polarstar f2~2000 rounds through it.
Redline SFR regulator
Prommy 455mm 6.03 barrel, lapped and R hopped with a prommy 70 deg bucking. All work done by Sherlockl from reddit
Maxx ME pro hop up
The problem: the m27 has very inconsistent groupings. The fps measures fairly stable at 344(.32)+- 1.5 measured with my acetech chrono. The bbs however will underhop and overhop pretty badly. The left and right deviation is great. I can send BBs to the moon and then flat and then slightly under-hopped in as many shots. This is most obvious when firing 2 round bursts
This is my most expensive and beloved rifle in my collection. I have sunk hours of work into it when I upgraded it as a AEG. It is also my worst performing rifle. The problem is either beyond my skills or is something simple that I am too frustrated to think through.
Let me know if you can help. I am happy to ship it anywhere in Canada if need be.
Some Troubleshooting I have done:
FCU settings: I have followed guides and am pretty sure I have the f2 volumed for my barrel length. Closed or open bolt mode make no difference. I feed every round in every mag I own.
Air leaks: Little bit of permatex gasket sealent under the bucking. Air lines from Amped. F2 clean and lubed.
Barrel: Cleaned with rubbing alcohol
F2: shimmed with a bit of tape so it doesn't move within the gearbox. Before I shimmed it would move fwd and back about a mm or so.
I can post a shooting video if needed.