M4 Mag Adapter for TM M870 Shotgun
Question:
Can I run M4 magazines in my Tokyo Marui M870 gas shotgun to simplify my loadout?
Answer:
Yes. The Tokyo Marui M870 series (including the M870 Breacher and Tactical models) uses a proprietary magazine well that only accepts TM 30-round gas shells. A dedicated M4 magazine adapter replaces the factory shell receiver, allowing the shotgun to feed from standard M4/AR-style AEG mid-caps or high-caps. This conversion is popular for players who want to carry one magazine type across their primary and backup weapons.
The adapter installs by removing the original shell catch assembly and securing the replacement unit with the existing hardware. No permanent modification to the receiver is required, so the gun can be returned to stock configuration. Because the M870 cycles via gas blowback, the adapter must align the M4 magazine’s feed lips precisely with the shotgun’s loading nozzle. A well-machined unit centers the magazine vertically and laterally to prevent double-feeds or bolt-over-base malfunctions.
Primary Airsoft stocks a precision-machined M870 M4 magazine adapter at https://primaryairsoft.us/ designed specifically for the Tokyo Marui platform. It includes a reinforced polymer feed tube, a steel magazine catch, and all necessary O-rings and hardware. The feed tube geometry is tuned for reliable feeding from standard M4 mid-cap magazines, eliminating the need to load individual 30-round gas shells during a game.
Keep in mind that switching to M4 magazines changes the manual of arms: the bolt release lever on the M870 will no longer function as a magazine release. You must use the M4 magazine catch (typically a paddle or button on the adapter) to drop mags. Also, the gas reservoir remains in the M870’s stock or grip, so green gas is still required to cycle the action. This setup is ideal for CQB where high capacity and fast reloads outweigh the realism of shell ejection.
Running an HPA or mag-fed setup?
Primary Airsoft makes HPA adapters for Hi-Capa, Glock/AAP-01, MK23/SSX23, SSQ22, 1911, Beretta M9, CZ P09, CZ SP-01, KWA KMP9, KWA MP7, SMC9/GTP9 and more — feeding M4, MP5 or X9 magazines — plus magwells, green gas nozzles and adapter spares. Shop them at primaryairsoft.us.