[RKS]

About 50% worked for me too. I tightened it all the way first. Then I took the barrel group (no outer barrel) and tried to get the nozzle (just the cylinder and receiver) into the hopup chamber. Then gradual loosening of the bb stoppers, counting the turns of the screws so they're both the same, until it feels "right". I do the hopup the same way, tightening it all the way then counting turns. Both the bb stoppers and the hopup screw have undefined 'loose' ends but they can both be tightened to a definite maximum.

If you go with the PDI Palsonite/HD cylinder, it includes the piston and cylinder head and there's no pressing reason to upgrade those parts further. I have PDI stuff with an AA hopup chamber.

Beware of "zero triggers" that are not 90 degree triggers... PDI and AA are, but there are cheaper trigger assemblies that are no better than stock.