Atlas Custom Works 6061 Aluminum 125mm Straight Fluted Outer Barrel for Hi-Capa GBB Pistols, Black

Atlas Custom Works' 5.1-inch straight fluted outer barrel is an aesthetic and protective upgrade for Tokyo Marui Hi-Capa GBB pistols. The fluting reduces weight while maintaining rigidity, and the 6061 aluminum construction handles field use without adding the bulk of a solid cylinder.

What an outer barrel does. It does not improve accuracy or range—that comes from the inner barrel and hop-up. An outer barrel protects the inner barrel from impacts, gives you a mounting point for suppressors or compensators, and changes the look of the slide assembly. On a Hi-Capa, swapping to a fluted barrel also breaks up the visual profile compared to the standard smooth cylinder.

Length. At 125mm (5.1 inches), this sits at the longer end for a pistol outer barrel.

Compatibility. Fits Tokyo Marui-spec Hi-Capa GBB pistols. If your slide has been machined for a different barrel profile or you're running a conversion kit, verify fit before ordering.

Installation. Outer barrel swaps on Hi-Capas often require fitting work—deburring, headspace adjustment, or slide machining depending on your build. If you are not experienced with Hi-Capa internals, have a gunsmith handle the install. The package includes the barrel and two O-rings; tools and installation services are not included.

Includes two O-rings for barrel retention.