Tactical Parts Tier 1 Gearbox (Ver. 2)

Built to order. Please allow up to 2 - 3 weeks for delivery.


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My most popular gearbox upgrade is now available as a complete drop-in kit! Unlike traditional "drop-in" AEG gearboxes, these are 100% complete and outfitted with a motor and motor grip with a perfectly shimmed motor-to-bevel gear engagement. No need to wonder if your gearbox is properly shimmed, or having to figure out if your pinion gear is compatible with your bevel! 

This fully assembled gearbox is built upon the rock-solid Retro Arms gearbox, which is CNC machined out of a solid block of billet EN AW 7075 T651 aluminum for unparalleled durability. The fully programmable Gate TITAN advanaced MOSFET offers extremely fast trigger response in addition to over 20 unique functions. The Siegetek gearsets are CNC Machined out of Chromium Molybdenum steel and are the strongest gearsets currently available.

I have selected the popular CYMA piston based on extensive testing in high-stress builds, and having shown itself easily capable of handling up to an M160 spring with ease. Every CYMA piston found in my Tier 1 gearboxes is AOE corrected with the second to last tooth removed and tested for proper engagement and clearances. The Lonex aluminum cylinder head is a proven performer and will not suffer from the vertical hairline cracking that can plague plastic cylinder heads. The Retro Arms double o-ring piston head is lightweight and strong and will not add unnecessary weight to the piston assembly and has a perfect seal within the Guarder cylinder.

The PTS EPG-C grip paired with these gearboxes offers an improved vertical grip angle, and will help reduce hand fatigue during long games.  

Note: Fits Version 2 compatible receivers only. This gearbox has been verified to fit G&P, VFC, and Krytac M4 style receiver sets. Due to varying tolerances between manufacturers, some minor fitting may be required with certain brands. 

Internal Features

  • Retro Arms CNC 8mm QCS gearbox
  • Krytac flat trigger
  • Lonex Ultimate selector plate
  • Krytac 8mm CNC steel bushings
  • Guarder precision oil tampered air nozzle
  • Lonex Ultimate tappet plate
  • Lonex double o-ring aluminum cylinder head
  • Guarder super lucid chromium plated cylinder
  • 70 degree Air-Pad (Gen. 2)
  • Retro Arms CNC POM double o-ring ported piston head
  • CYMA 14t FMR piston / AOE corrected
  • Siegetek 20:8 balanced gearset
  • Lonex anti-reversal latch
  • Prometheus M120 spring
  • ASG high torque motor
  • Deans plug

MOSFET Features

  • Trigger sensitivity adjustment
  • Pre-cocking boost
  • Cycle detection
  • Fully adjustable Active Braking
  • Fire selector mode
  • Battery protection
  • Low battery Warning
  • Burst mode
  • ROF control
  • Sniper Delay
  • Optional 30 round limiter

Additional Specs

  • 400 FPS +/- w/.20g BB
  • Fully shimmed
  • AOE corrected piston
  • Compression verified
  • Rear wired for buffer tubes or fixed stocks
  • Quick Change Spring (QCS) guide
  • PTS EPG-C motor grip promotes improved grip angle for all-day comfort
  • 30 day warranty
*Parts substitutions may be made based on availability. If a substitution is made, parts of equal or greater quality will be used in your build.