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EMG / Maxx Model CNC Aluminum Hopup Chamber for M4 / M16 Series Airsoft AEG Rifles (Model: M4A / EMG Blue)

EMG / Maxx Model CNC Aluminum Hopup Chamber for M4 / M16 Series Airsoft AEG Rifles (Model: M4A / EMG Blue)
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Hopup unit may require assembling
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EMGMaxx Model Products


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The manufacturer of this product enforces a strict minimum advertised price (MAP) policy which excludes this product from any additional discount coupon codes. This item, however, may qualify for free shipping.
Model Options:


  • Machined from a solid aircraft aluminum block with tight tolerances to provide better accuracy, consistency, and durability
  • Precision rotary dial design for fine hopup adjustments
  • Re-engineered the hopup levers and concave nubs to work best with R-hop, Flat-Hop and Standard-Hop to keep the BBs shooting straight and accurate on every single shot
  • Accepted the nozzle length from 21.00mm to 21.25mm
  • Fully compatible with most aftermarket soft and hard rubber bucking without losing FPS or dropping BBs
  • Equipped with a new CNC Delrin Locking C-Clip design to hold barrel tight without wobbling and twisting, 3 compression springs on top, at bottom and in center of housing to ensure the hopup unit is exactly centered, straight and air tight
  • Compatible with any V2 gear boxes with 11mm or 11.5mm bore
  • Specially designed with BB Latching System to prevent dropping BBs after removing the magazine, Manually opened to release BBs from inside hopup chamber by hand
CNC Aluminum Hopup Chamber M4A Pro (with BB Latching System) unit is precisely machined to perform accurately and consistently on Tokyo Marui (include G&G, KRYTAC, except KWA) Standard M4/M16 AEG series rifles.

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 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 BBs 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. 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 tightly in place without wobbling and twisting.

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

***Test results: FPS might be increased by 5% to 10%. Please check your FPS!

Manufacturer: EMG / Maxx Model


Hopup Kit Includes:
  • 1 x CNC Aluminum Hopup Chamber M4A Pro (with BB Latching System) unit
  • 2 x CNC Acrylic Side Cover
  • 2 x CNC Brass 2.5mm Side Wing
  • 1 x CNC Steel Pivot Pin
  • 1 x CNC Aluminum Hopup Lever
  • 1 x CNC Aluminum Soft Round Nub
  • 1 x CNC Aluminum Soft Flat Nub (4mm)
  • 1 x CNC Aluminum Hard Concave Nub (4mm)
  • 3 x Steel Nub Spring
  • 1 x CNC Steel Spring Guide
  • 1 x Steel Upper Compression Spring
  • 1 x Steel Center Compression Spring
  • 1 x CNC Delrin Locking C-Clip
  • 1 x CNC Brass Barrel Spacer
  • 1 x Brass Barrel Spacer Holder O-ring
  • 1 x CNC Aluminum Rotary Dial Knob
  • 1 x CNC Aluminum Inlet Adaptor (OD11mm)
  • 1 x CNC Brass Inlet Spacer

  • Overall Length: 51.65mm
    Overall Height: 37.75mm
    Inlet Adaptor Outer Diameter (to fit into Gear Box): 11mm
    Hub Outer Diameter (to fit into Outer Barrel): 12mm
    Hub Inner Diameter (to fit Nozzle): 8mm
    Feeder Outer Diameter (to fit magazine): 8.85mm
    Feeder Length (to fit magazine): 6mm
    Application: For most Tokyo Marui (include KRYTAC, except KWA) M4/M16 standard AEG version 2 gear box
    Material: Aluminum 6061

    About EMG

    The EMG vision is to manufacture products the world has never seen before; products we would put our name on, and products that hit the spot! "EMG" (Evike Manufacturing Group) was spawned from the realization that if you want something done exactly the way you want it, you need to do it yourself, and we did just that.
    We took our 16 years of knowledge as the market's lead retailer, our network of 300+ superior manufacturers, to work with inspiring top innovators in the firearms industry. That combined with the vision to invest into the Airsoft industry, an industry we believe in, EMG was born.

    About Maxx Model Products

    Maxx Model Products design, manufacture, and make high quality parts for Airsoft products.

    21 Customer Reviews

    (Write a review)

    by Lincoln L. on 07/13/2023
    "Just received this hop up and man it's way better than my stock cyma hop. It works awesome with the new Bucking and barrel I got with it! It comes ready to install and is just a plug and play really. It is on the expensive side but I personally think it's worth it if you have that kind of money. Would recommend to a friend.
    by Tomas A. on 07/05/2023
    "I Did not get my parcel yet the only reason I am writing this is that It will not let me do anything else on my account
    by Daniel P. on 05/05/2023
    "By far the best thing I did to my cyma m16 was this, a barrel and a bucking. I picked up ~30 FPS and has much better range and accuracy. Much better adjustment over stock. Everything that a hop up does, this does it better.

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