CNC Aluminum HopUp Chamber M4A - PRO

The highest quality HopUp chamber designed for tuning M4 / M16 replicas. Rotary chambers manufactured by Maxx Model Products are made for the most demanding of players, they offer precise workmanship that is unprecedented on the market and perfect operation of the HU system in the replica.

80,56 € tax incl.

Availability: In Stock

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25. 07. 2024 (50 pcs.)

13 pcs.



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CNC Aluminum HopUp Chamber M4A - PRO (with BB Latching System) unit is precisely machined to perform accurately and consistently on Tokyo Marui (include G&GKRYTAC, except KWA) Standard M4/M16 AEG series
The Hopup Chamber M4A unit is built with an aluminum Rotary Dial Knob for fine hopup adjustments, the precision Hopup Lever and 4mm Bucking Nubs (6mm Bucking Nubs are optional) to perform best with R-Hop and Standard-Hop to keep the BB shooting accurately and consistently on every single shot.

The Hopup Chamber M4A unit is designed to accept 21.00mm to 21.25mm nozzle length, and fully compatible with most aftermarket soft and hard rubber buckings without losing FPS or dropping BB during use. 

The Hopup Chamber M4A unit is wisely equipped with an interchangeable Inlet Adaptor OD11mm to ensure the hopup unit is inserted exactly in the center of the 11mm inner bore AEG Gearbox/HPA Engine nozzle outlet without wobbling. (Inlet Adaptor OD11.5mm and OD12mm are optional) 
Also mounted the removable CNC Brass Side Wings to slide smoothly into the outer barrel slots, and included an advanced CNC Delrin Locking C-Clip to hold the inner barrel tight in place without wobbling and twisting. 

More than that, the Hopup Chamber M4A Pro unit is specially designed with a new BB Latching System to prevent BB dropping after removing the magazine. The Latching Arm can also be manually pressed to release the remaining BB from inside the hopup chamber.


  • precisely made of a block of aviation aluminum using CNC technology
  • compatible with M4 / M16 carbine replicas in the Tokyo Marui standard (including G&G or Krytac replicas, but NOT KWA)
  • rotary knob for adjustment
  • redesigned precise HopUp and 4mm Bucking Nubs levers (6mm versions are optional), ensuring troublefree operation with standard and Rhop elastics
  • Removable steel Pivot Pin for setup and maintenance
  • works with nozzles with a length of 21.00mm to 21.25mm
  • full compatibility with most soft and hard HU elastics available on the market, with zero FPS drops and balls falling out
  • equipped with a special CNC Delrin Locking CClip, preventing vibration and barrel movement
  • equipped with 2 compression springs at the top and in the middle of the chamber, ensuring a perfect and secure fit in the replica
  • equipped with an 11mm Inlet Adapter for the gearbox (11.5 and 12mm versions available separately) to ensure the central arrangement of the nozzle in the chamber and reduce wobble
  • added, replaceable brass side wings to improve the fit of the chamber in the outer barrel
  • redesigned "BB Latching System", preventing the BBs from falling out after removing the magazine from the replica
  • the latch arm holding the BB’s can be pressed by hand to release the BB’s from the chamber
  • possibility of mounting a BB tracer unit (not included)


  • For: M4 / M16 TM, Krytac and G&G Replicas
  • Material: aluminum 6061
  • Weight: 20g
  • Colour: red
  • Manufacturer: Maxx Model Products
  • Length: 51.65mm
  • Height: 37.75mm
  • Hub Outer Diameter (for the gearbox): 11mm
  • Hub Outer Diameter (for the outer barrel): 12mm
  • Hub Inner Diameter (to the nozzle): 8mm
  • Feeder Outer Diameter (for magazine ): min 8.85mm
  • Feeder Length (for magazine ): max 6mm
  • Execution: Aluminium 6061

The set includes:

1 x CNC chamber with BB Latching system
2 x clear CNC vinyl cover
2 x 2.5mm CNC Brass Side Wing
1 x Steel CNC Pivot Pin
1 x HopUp CNC aluminum arm
1 x Aluminum Soft Round Nub CNC
1 x Aluminum Soft Flat Nub CNC (4mm)
1 x Aluminum Hard Concave Nub CNC (4mm)
3 x steel Nub Spring
1 x steel CNC spring guide
1 x steel top compression spring
1 x steel central compression spring
1 x Delrin Locking CClip CNC
1 x Brass CNC Barrel Spacer
1 x Brass Spacer Holder Oring
1 x CNC aluminum adjustment knob
1 x Aluminum Inlet CNC Adapter (11mm)
1 x Brass Inlet Spacer CNC

Gearbox versionV2
Hop-Up chamber materialMetal