GTP9/SMC9 to M4 HPA Adapter
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**COMING SOON - Updated 2026 edition with high quality, near indestructible, injection moulded polycarbonate M4 magwell.**
Features:
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Compatible with short GTP/SMC9 gas magazine
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CNC Mag Release and Feed Tube
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Includes single stack adapter
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BB retention mechanism to reduce BB loss during magazine changes
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US HPA FITTING as standard
We’ve taken feedback on thousands of M4 HPA adapters sold throughout 2022, to build what we believe to be the perfect HPA adapter. A CNC feed tube and recessed CNC mag release provide lifelong longevity, a flared magwell enables speedy mag changes, and an adjustable shim gives excellent magazine compatibility and fitment (though you won’t need it for most magazines!).
Our whole team worked their magic in creating a beautiful aesthetic that suits the pistol, while still allowing the use of flared mag-wells and keeping bulk to a minimum.
It doesn’t end there, we offer excellent product support, lifetime warranty, and include spare parts should you or your team ever need them!
Assembly - YOU WILL NEED A QUICK GRIP STYLE CLAMP
Installation is dead simple, you’ll need a quick grip vice such as this, a pin punch (2mm), basic screwdriver set and a hammer or mallet.
1) Punch out the bottom pins on the sides of the gas magazine to remove the gas block.
2) Punch out the small pin that retains the follower at the bottom of the gas magazine
3) Insert the single stack adapter into the gas magazine
4) Fit the gasket to the Airtac HPA adapter (at this stage you can apply some silicone oil to the gasket to aid insertion )
5) Place the HPA Adapter into the magazine, and into the clamp. Tighten the clamp until the pin holes line up, and gently hammer them in.
6) Go have fun!
DO NOT EXCEED 150PSI WITH ANY AIRSOFT HPA ADAPTER.
ALWAYS USE AIR REGULATED BY A SECONDARY REGULATOR (EG AT200, WOLVERINE STORM, POLARSTAR MRS).
CHECK YOUR PSI BEFORE CONNECTING AIR TO A HPA ADAPTER.
NEVER CONNECT OUR EQUIPMENT TO PAINTBALL AIR TANKS OR CO2 TANKS.
NEVER CONNECT OUR EQUIPMENT TO A TIPPMAN STYLE HPA LINE
AIRTAC Adapters
Each of our adapters is designed to be low profile while reaching field limit FPS. We design and manufacture all of our products to the highest standard, and do not charge extra for ‘premium’ features. Where applicable this adapter features:- Lifetime Warranty (Our adapters have to be built to last)
- Injection moulded or CNC magwell that is impervious to BB strikes at point blank skirmish FPS.
- CNC or Injection moulded Feed Tubes and Magazine Catches for lifelong durability.
- Tuneability/compatability via integrated shim systems. Our adapters are designed to cope with 'airsoft tolerances'
- Gas Routers injection moulded from NBR, 1:1 with the factory gas router.
- Seal Test
- Firing test, for feed and recoil (we have over 100 guns on site for testing)
Compact MP5
M4 Adapter Information
- Injection moulded from polycarbonate, this magwell is near indestructible!
- Compatible with most airsoft M4 magazines.
- We recommend EPM1/EPM1s magazines as they have excellent fitment and strong springs.
- Magazines advertised as Fast Feed such as the original EPM or Amarok magazines will also work well
- BB retention means only 2-3 BBs are dropped when changing mag
- A swappable rear shim is included
Key Information
- We use a US Foster Fitting as standard. This is the most common airsoft HPA fitting. EU fittings can be purchased separately.
- Some of our HPA adapters have a smaller internal volume than gas magazines. Because of this, you will need to use a PSI of 90–150.
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If you need higher FPS, you can:
- Fit a tighter barrel
- Use a longer barrel
- Use heavier BBs
- Fit an improved hop bucking
- If your replica has an NPAS fitted, we advise opening it fully.
- Do not exceed 150 PSI. Many airsoft guns will not see an increase in FPS past this, as the hammer may struggle to depress the valve correctly.
- Insert the HPA adapter with your bolt / slide locked back to minimise pressure against the nozzle loading arm.