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M4 Magazines in a Pistol? Your Guide to HPA Mag Adapters!

Published 2024-02-07 by Tyler J.

What are HPA AEG Mag adapters and how do they work?

Handguns are considered sidearms for a reason. The short barrel length makes reaching velocities over 350 a fantasy, and the diminutive 20-30 round magazines seriously handicap your firepower when pressed against high capacity rifle rounds. Sure, they’re compact and easy to holster on the hip for a quick-access backup in case your rifle becomes inoperable, but you wouldn’t run them as a primary weapon, right?

Oddly enough, running a pistol as a primary is by far one of the most fun ways to enjoy airsoft. It’s difficult to explain just how much of an advantage a smaller weapon profile can grant without offering the experience of charging into battle with one. Corners become your best friend, as you can tightly weave around obstacles with far more deftness than any rifle user. You’re likely going to be at the disadvantage when it comes to range and accuracy, so you’re going to have to get close. Getting close requires you to charge head on into the fight, allowing you to experience the thrill of a high speed playstyle. With a handgun, speed, surprise, and skill are key to taking eliminations.

The speed of the handgun playstyle is a double edged boon. Though you may have a degree of dexterity that your rifle-equipped opponent can only dream of, you’re also going to be burning those resources far faster. The average M4 magazine will typically be carrying around 6x as much ammunition as your pistol magazines, putting you in a poor position when it comes to situations where extended pressure and firepower are necessary. A pistol will most likely lose in a firefight of attrition. Can handguns really stand a chance against rifles with such an ammo capacity disparity?

Absolutely! That is, so long as you’re running an M4 Magazine adapter for your pistol! It may look a tad silly, but when you combine the high capacity magazines of an AEG with the compact gas blowback action of an airsoft pistol, you’ll be wielding a serious threat to be reckoned with.

Let’s begin with the adapter that set in motion this accessory’s wave of popularity:



Custom Hi-Capa builds have long been a fashionable secondary in the airsoft world. Though they excel when it comes to close quarters combat, more open outdoor fields with long distance engagements might relegate those fancy sidearms to being… well… just a sidearm. The release of the HPA to M4 magazine adapter changed that completely, giving one enough firepower to use your souped-up handgun as a viable primary weapon with loads of ammunition to shower down upon your opponents.

Setting one of these adapters up isn’t exactly as simple as just buying the part. In addition to the adapter, here’s what you’re going to need to get one of these running.

List of Accessories Needed to run a Pistol M4 Mag Adapter:

  • HPA Tank: A basic green gas pistol magazine holds just enough gas to shoot the 25-30BBs you fill it with. With one of these adapters, you’re going to need a much bigger gas reservoir. I recommend the Valken V2.0 48ci 3000 PSI Paintball Compressed Air System DOT/TC/Pi

  • Air Regulator & Hose: This is the connective piece between your tank and HPA adapter. From this regulator, you can adjust the pressure being sent into your pistol, giving you some room to adjust velocity and system wear. I recommend the Redline Airsoft Mini SFR Air System (Model: HPA Engines)

  • Green Gas Magazine: These adapters replace the base of your existing green gas pistol magazine. Make sure you have the proper brand for your given adapter or your magazine may not fit correctly!

  • Proper AEG Magazine: Of course, you’ll need the magazine that your adapter can adapt. Not every AEG magazine will fit the same on these adapters! Take care to ensure your magazine of choice will fit and feed.



Once you’ve gathered all the accessories, you’re ready to go! Most airsoft fields and shops should be to fill the HPA tank, and once you attach the regulator I’d recommend tuning it to around 110-120 PSI for most pistols. Unscrew the bottom portion of your green gas magazine and, using the long included hex screw, carefully screw in the adapter. Make sure to apply each O-ring properly!


Looking for something a little more durable and stylish? Check out the Poseidon Stormbreaka Adapters!



Running an AAP-01? The CTM adapter might just be the one!


Pistols aren’t the only GBB platforms gifted with the luxury of M4 mag adapter accessories. Here are a few other adapters that bring the versatile and high capacity AEG mag system to other gas platforms:


The Tokyo Marui MWS is an awesome GBBR! Make it even more awesome by giving it the gift of 150+ round magazines! More recoil, more shoot, more fun!


HPA isn’t necessary for this adapter! Ditch the 30 round shotgun shells and use M4 magazines in your airsoft shotgun!

Admittedly, the wonky aesthetic of having a strangely large magazine attached the bottom of your pistol can distract from any real-steel immersion. Some players even prefer the realistic capacity of their gas systems for training purposes. If you prefer to stay competitive on the airsoft field with a high performance gas blowback system that sends a satisfying smack of recoil into your shoulder with every shot, these adapters might just be perfect for you. After all, when aiming down your sights, that magazine adapter isn't going to be part of your first-person vision. It's all about the experience with these! Dominate your next game by bringing your gas gun to it's fullest potential!
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