CNC Aluminum Hopup Chamber M4P Pro (with BB Latching System) unit is precisely machined to perform accurately and consistently with HPA PolarStar Engines on standard M4/M16 platform.

The Hopup Chamber M4P 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 M4P unit is designed to accept the HPA PolarStar Engine M4 nozzle length, and fully compatible with most aftermarket soft and hard rubber buckings without losing FPS or dropping BB during use.

The Hopup Chamber M4P 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 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 M4P 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.

***Test results: FPS might be increased from 10FPS to 30FPS over the stock setup. Please check your FPS!

Includes

• 1 x CNC Aluminum Hopup Chamber M4P 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 Oring
• 1 x CNC Aluminum Rotary Dial Knob
• 1 x CNC Aluminum Inlet Adaptor (OD11mm)

Specification

• Overall Length: 51.15mm
• Overall Height: 37.75mm
• Inlet Adaptor Outer Diameter (to fit into HPA Nozzle Outlet): 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
• Material: Aluminum 6061

Features:

• Machined from a solid aircraft aluminum block with tight tolerances to achieve the most accuracy, consistency, and durability
• Performed accurately and consistently with HPA PolarStar Engines on standard M4/M16 platform
• Precision Rotary Dial Knob for fine hopup adjustments
• Re-engineered 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
• Removable Steel Pivot Pin for ease of setup and maintenance
• Accepted the HPA PolarStar Engine M4 nozzle length
• Fully compatible with most aftermarket soft and hard rubber buckings without losing FPS or dropping BB during use
• Wisely equipped with an interchangeable Inlet Adaptor OD11mm to ensure the hopup unit is inserted exactly in the center of the 11mm inner bore HPA Engine nozzle outlet without wobbling. (Inlet Adaptor OD11.5mm and OD12mm are sold separately)
• Mounted the removable CNC Brass Side Wings to slide smoothly into the outer barrel slots
• Included an advanced CNC Delrin Locking C-Clip to hold the inner barrel tight in place without wobbling and twisting
• Equipped with 2 compression springs on top and center to ensure the hopup unit is seated straight and air tight during use
• 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
• Compatible with any 11mm inner bore HPA Engine nozzle outlets
• The Dual UV LED Tracer Module to glow BB in the dark ready!

Don't forget - if you aren't confident in carrying out your own weapon servicing, repairs or upgrades, we have experienced airsoft technicians in-store and can do the work for you. You can even book a service with us online by clicking this link!

Book a Gun Service.

To buy an airsoft weapon in the UK you must have a valid airsoft defence.

This is not a licence, it is basically just proof that you intend to buy an airsoft weapon for use in airsoft.

An airsoft defence could be a UKARA or membership with the British Airsoft Club, and various other forms of defence.

You can only obtain an airsoft defence once you are over the age of 18.

To get an airsoft defence the law is that you should play at least 3 games of airsoft, and that you must have been playing for at least two months.

You can still buy an airsoft gun without a defence, provided you are 18 or older. If you choose to do this we would, by law, two tone (paint in a bright colour) parts of your chosen weapon. This is because an airsoft gun is considered a RIF aka Realistic Imitation Firearm, because they are so close to the real steel, whereas when you paint parts of it in a bright colour it becomes an IF aka Imitation Firearm. The reason being that the bright colours make it look less realistic to the public, and therefor less likely to be mistaken as real, were it to be used for any other purpose than airsoft.

When you order a gun from us you will need to add your defence details in the comments section of the cart. If you do not have a defence you will need to write the colour that you wish to be used for two toning your airsoft weapon.

Here is what's stated in the VCRA (Violent Crime Reduction) Act:

For airsoft skirmishing, the Association of British Airsoft is putting in place arrangements to allow retailers to check that individual purchasers are members of a genuine skirmishing club or site. The key elements of these arrangements are:
1. new players must play at least 3 (three) times in a period of not less than two months before being offered membership
2. membership cards with a photograph and recognised format will be issued for production to retailers
3. A central database will be set up for retailers to cross-check a purchaser’s details
4. member’s entry on the database will be deleted if unused for 12 months.
The defence for airsoft skirmishing can apply to individual players because their purchase of realistic imitation firearms for this purpose is considered part of the “holding” of a skirmishing event.