Block2 Build – Mechbox buildup

Parts list:

  • Siegetek 10.44:1 single-sector gearset
  • Siegetek pinion gear
  • ASG Ultimate U-18000 28TPA motor
  • SHS 8mm steel bushings
  • BTC Spectre
  • Lonex V2 cylinder head
  • Lonex M4/M16 nozzle
  • SHS ultralight piston
  • Rocket Airsoft POM piston head
  • 1/8″ Sorbo pad
  • Retro Arms straight trigger
  • ZCI steel full cylinder

The factory glued-in bearings had to be knocked out to make way for the more reliable bushings. Nice of VFC to glue them in, but not sure why they moved away from the solid bushings. Gains from bearings are minimal.


Siegeteks are dropped in and shimmed to sub-0.5mm tolerance.


The Rocket Airsoft piston head was chosen in lieu of the usual Lonex POM head due to comparable weight (5.33g for the RA; 5.1g for the Lonex) and substantial cost difference. Also, the Rocket Airsoft head is thicker which contributes to AoE correction.

The rest of the parts are pedestrian as per usual. The whole gearbox is shown complete and ready to close with any requisite tuning done along the way.



Up next: Barrel Group

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