I traded my AKS74U for the M249. I have a few new parts in it already but the tuning is the bigger deal. First off, the motor is utter garbage. Its not even worth using it as a paper weight due to the embarrisment ensuing suck a terrible conversation piece. CRAP! CRAP! CRAP!

VXB 3x8x3 closed bearings (much easier to shim with these)
PDI 190% spring
Systema standard torque gears
Systema type 1 cylinder
CA hopup unit
CA hopup bucking
Guarder metal bearing spring guide
Prometheus & Modify shims (yes it was necessary)
Prometheus hard type piston

I still need to overhaul the eletrical side of the AEG
It really need a motor. I'd like a G&P 160