Contact Us Tel:(626) 286-0360 Store Locations
Phone Support M-F 7am-5pm PST
Browse by Type or Category
Black Friday Deals start NOW! Shop early for the holiday season with FREE SHIPPING on orders over $149!

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

ID: 102034 (HU-MX-MX-HOP010MA)
Maxx Model ProductsMX-HOP010MAMX-HOP010MA102034
4.7 stars, based on 34 reviews
Maxx Model CNC Aluminum Hopup Chamber for M4 / M16 Series Airsoft AEG Rifles (Model: M4A - PRO)
Hover or touch above to zoom
Hopup unit may require assembling
Product image 1
Maxx Model Products


MAP ProtectedExempt From Coupons
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.
Size 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 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
  • 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 11mm inner bore AEG Gearbox/HPA Engine nozzle outlets
  • 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.

Manufacturer: Maxx Model

Color: Red

Size: M4A - PRO


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

    Test Results: FPS might be increased from 10FPS to 30FPS over the stock setup. Please check your FPS!
    Disclaimer: Professional installation highly recommended. Please use discretion when installing custom parts as fit and compatibility may vary. Modification may be required. Professional installation recommended.

    About Maxx Model Products

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

    34 Customer Reviews

    (Write a review)

    by Dartagnan P. on 09/08/2022
    "Slammed one of these in a stock new G&G combat machine with a brushless motor, modify bucking and a laylax tightbore barrel. performance is stellar, the latch system is great, the window in which you can finally visibly see the bbs is great. everything is great about it honestly, if you want to up your performance overall get one! comes already assembled out of the box with 3 in total hop up arms very sturdy and all around will last you a VERY long time

    also to MY understanding the Maxx Pro M4A is meant for most AEG's.... again just my understanding, i could be wrong
    by Madison M. on 05/10/2022
    "Got this in my new MARS II Carbine. I've used the standard model in a few ICSs before and they work with minor modifications. This time I got the proper MI PRO version and it fits perfectly with no needs to changes. It's a little better than the stock chamber (ICS use the same style as stock) but I like that it has r and flat hop capabilities designed in.
    by Patrick B. on 04/05/2022
    "I got an MI Pro for my ICS EBB based build. Another reviewer said the 21mm nozzle didn't work for their application, but it worked fine for me. Depends on your individual build. Both the nozzle and the hop up unit increased FPS by about 15~

    Measured with a digital caliper, the stock ICS nozzle was 20.9mm and the SHS AK Long nozzle was 20.7mm. The Maxx 21mm nozzle gave me a 5 fps bump over stock. The SHS AK Long dropped fps by 30. Compression with the AK long was good, but it would cause a gap between the nozzle and the bucking since it was too short. Although, they all fed EF .25s out of a KWA K120 @ 26 RPS.

    5/5 if you can get it to work

    Comments & Community

    Discuss about Maxx Model CNC Aluminum Hopup Chamber for M4 / M16 Series Airsoft AEG Rifles (Model: M4A - PRO) with your friends and fellow shoppers!

    Have an urgent question about this item? Contact us, our resident experts are standing by to answer your questions!

    California Proposition 65 Warning: Cancer and Reproductive Harm -

    Customers who bought this also purchased

    Parts and accessories may not be compatible with the product displayed on this page. For compatible parts/accessories, see the You May Also Need section and please verify details on the product description page.