Biorage: I replaced the stock VFC unit because it had a prominent mold line right through the middle of the hop arm. I suppose i could sand it down and try it. I have 2 lonex units in my drawer. The problem was just as bad with them as with the Maxx. One problem with the lonex units was the tiniest hair of an adjustment would cause huge changes in amount of hop applied.
R.I.T.Z.: I have looked at nozzle alignment quite a lot. The left and right alignment is perfect while the nozzle is a hair high. I have checked nozzle alignment with and without a mag full of BBs pushing up against the nozzle. Closed and open bolt make no difference. BB brands that I have tried: Elite force, Valken (I know these are shit), Gryphons ( They dont make bio .32
). I want to spend lots of money on super high end heavy weight BBs but i cant justify the purchase until I tame this Hop problem. My other rifles get consistently better performance with the same BBs. Rhop was done by Sherlockl from the airsoft Subreddit. I dont know how to install R hops but he comes highly recommended.
Pestobanana: I researched this phenomenon before buying the HPA engine and one of the selling points of the polarstar F2 is it uses a spring to push the nozzle forward and load a BB. I just tried firing the engine into my thumb and it feels identical to my AEGs. The nozzle problem isint one I have explored though. Through the maxx hop window (without lighting module) it doesent seem like the nozzle pushes far into the bucking. However as I detailed in my above post the F2 did move a tiny bit front to back. I would put a strip of tape at the 12 o clock position "cylinder head" part of the f2 engine to 1: move the nozzle down slightly and 2: stop the engine moving back and forth. I would always shim the engine as far forward for maximum nozzle to bucking airseal. I guess I can shim in the rearward position and see if there is any improvement but there really is so little movement that I am not optimistic. I never have had a BB roll out on me when hop is applied.
Thanks for your responses guys but I have spent a LOT of time on this problem and googling around. Ill have another look at it but I am feeling like I need a fresh set of eyes on this problem.
All the best!