Atlas Custom Works Aluminum Outer Barrel for Hi-Capa 5.1, Gold

The Hi-Capa 5.1 is one of the most popular GBB pistol platforms in airsoft, and swapping the outer barrel is a straightforward way to change the look and upgrade durability. Atlas Custom Works machines this aluminum barrel to match Tokyo Marui's dimensions, so it fits the stock slide and internals without modification. The gold finish is cosmetic — it does not signal a different length, thread type, or internal specification.

What the swap does. The aluminum barrel replaces the factory polymer piece, which can scuff or crack after repeated draws from a holster. Metal resists that wear, and the added weight is negligible. Because the outer dimensions stay the same, your existing slide, grip, and mounting accessories remain compatible.

What it is not. This is not an accuracy upgrade. The outer barrel does not touch the BB, so it does not affect grouping or range. If you want better precision, that work happens at the inner barrel and hop-up level. This barrel is for durability and aesthetics.

Installation. Swapping the outer barrel requires removing the slide assembly and pressing the old barrel out. The job takes ten minutes with basic tools, but if you have never field-stripped a Hi-Capa, watch a guide first or have a tech do it. You get the outer barrel only — the inner barrel, hop-up chamber, and all internals remain yours.