Understanding HPA Adapter Thread Types
Question:
I want to run my gas blowback pistol on HPA, but I'm confused about the different adapter thread types. What is the difference between an M4-threaded adapter and an MP5-threaded adapter, and how do I know which one fits my specific magazine?
Answer:
The thread type refers exclusively to the input side of the adapter—where your HPA line connects—not the magazine itself. This is the single most common point of confusion for players converting gas pistols.
M4-threaded adapters feature a standard 1/8" NPT female thread. This is the industry standard for the vast majority of HPA regulators and air lines (PolarStar, Redline, Wolverine, Amped Airsoft). If you own a standard HPA rig with a tank, regulator, and coiled hose, you almost certainly need an M4-threaded adapter.
MP5-threaded adapters utilize a proprietary metric thread (roughly M8x0.75) designed specifically for the Action Army / Tippmann MP5K HPA kit. This kit uses a unique quick-disconnect fitting integrated directly into the magazine well of the MP5K. These adapters will not screw onto standard 1/8" NPT fittings found on typical regulators or remote lines.
Magazine compatibility is determined by the "output" side (the baseplate). Whether you choose M4 or MP5 thread input, you must select the specific baseplate model for your magazine: Tokyo Marui Hi-Capa/1911, Action Army AAP-01, Glock (TM/WE/VFC), MK23/SSX23, SSQ22, Beretta M9, KWA MP7, G-Series, or MP5.
If you are building a standard HPA pistol setup with a remote line and regulator, select the M4-threaded version of the adapter for your specific magazine model. Only choose MP5-threaded if you are installing it into an Action Army/Tippmann MP5K HPA conversion kit. For the correct baseplate and thread combination, browse the catalog at https://primaryairsoft.us/.
Running an HPA or mag-fed setup?
Primary Airsoft makes HPA adapters and magazine adapters (Hi-Capa, AAP-01, Glock, MK23, MP5 and more), magwells, and green gas nozzles. Shop them at primaryairsoft.us.