MAG Tactical Systems MG-G4 Gen 4 9mm AR-Style Carbine with 16" Threaded Barrel & M-LOK Handguard
This MAG Tactical Systems MG-G4 Gen 4 stands out for its ultralight magnesium/aluminum lower, custom 9 mm blowback upper, and Stern Defense MAG-AD9 adapter that lets the carbine run reliable Glock-pattern magazines with last-round bolt hold-open. A 16-inch pencil-profile barrel, full-length 15-inch M-LOK handguard, and collapsible stock round out a build that balances weight, control, and modern modularity.
Condition
Overall Condition: Good – shows some signs of prior use and handling.
Bore Condition: Good – clean, well-maintained, minor wear marks.
Rifling Condition: Good – intact, well-defined lands and grooves.
Specific Condition Notes: Light handling marks are present on the exterior. The bore is bright and free of fouling.
What’s Included
- MAG Tactical Systems MG-G4 Gen 4 9mm carbine
- One Amend2 34-round Glock-pattern magazine
The MAG-G4 lower receiver weighs under six ounces yet retains AR-15 controls, thanks to its proprietary magnesium/aluminum alloy construction and integral oversized trigger guard. MAG Tactical Systems ended production around 2017, so complete rifles built on these lowers are increasingly uncommon.
This rifle is configured with a dedicated 9 mm blowback upper. The slick-side receiver eliminates the forward assist and dust cover for reduced weight and a clean profile. A 16-inch pencil-contour barrel keeps the front end light while retaining the 1/2-28 UNEF threads for muzzle devices or suppressor mounting.
The Stern Defense MAG-AD9 adapter allows the use of Glock-pattern magazines and provides a functional last-round bolt hold-open—an important feature that many 9 mm AR builds lack. The adapter installs without permanent modification and can be removed if the owner wishes to revert to a standard AR-15 caliber.
A 15-inch free-float aluminum M-LOK handguard offers generous space for accessories across its full length while protecting the barrel during sustained fire. Flip-up polymer sights give immediate aiming capability and fold flat when an optic is installed.