Definitely not "correct", but I loved building this gun (both internally and externally).
Cyma AKs-74u
Internally I pretty much completely re-did it.
-Lonex A1
-Lonex POM piston head
-SHS gen 1 13:1 gearset
-SHS 7 steel toothed piston
-SHS 110 spring
-Guarder o-ring air nozzle
-SRC metal spring guide with bearing
-SRC metal double o-ring cylinder head
-R-hopped 300mm madbull 6.03 barrel
-Pro Win hopup chamber
-wired to deans
-re-shimmed and AOE corrected
Ya... I think that's everything, lol. It sure is a fast shooting gun now.