Brownells Brn-Gau-5A Upper Receiver, 11.5'', 1-12 Twist, Black

The Brownells Brn-Gau-5A Upper Receiver in 11.5" with 1-12 twist barrel is built for shooters chasing authentic early-carbine vibes without compromise on function. This is a complete, ready-to-run upper assembly that captures the distinctive look and spec of Vietnam-era XM177/GAU-5 configurations—the kind of retro build that appeals to historians, collectors, and anyone who appreciates purposeful rifle design. At 11.5" barrel length, this upper delivers compact handling while the chrome-lined bore and chamber stand up to whatever ammunition you feed it.

What sets the GAU-5A apart is the attention to period-correct detail. The XM177-style flash hider (a true flash hider, not a suppressor) sits at the muzzle with its characteristic radial ports, paired to that lightweight 11.5" barrel. The M16 slick-side receiver omits the forward assist and shell deflector, staying true to early military carbine design. You'll recognize the carbine-profile handguards with integrated heatshields and the A1 rear sight aperture that adjusts with a standard cartridge or tool. The tapered slip ring is exactly where it should be on a proper vintage-pattern upper.

Everything here is mil-spec or better: the included manganese phosphate bolt carrier group features a 9310 bolt with chrome-lined interior, and the ejection port cover is a correct M16A1 type, not an off-the-shelf generic. If you're building a retro AR or restoring a configuration that matters, this upper does the legwork so you don't have to hunt down individual parts or second-guess authenticity.

Key Features

• M16 slick-side upper receiver without forward assist or shell deflector
• XM177 flash hider with grenade ring at muzzle
• 11.5" 5.56x45mm NATO barrel, 1-12 twist rate
• Chrome-lined bore and chamber for durability
• Manganese phosphate mil-spec bolt carrier group with 9310 bolt
• M16A1 ejection port cover (proper profile, not generic)
• A1 rear sight assembly with adjustable aperture
• Carbine-profile black polymer handguards with heatshields
• Tapered slip ring—correct for early carbine pattern
• Includes bolt carrier group; ready to pair with a lower receiver

Specifications

Frequently Asked Questions

Is this a complete upper receiver ready to shoot?

Yes. The Brownells Brn-Gau-5A upper comes fully assembled with the bolt carrier group installed. You'll need to pair it with a compatible AR-15 lower receiver to complete a rifle.

What's the difference between the 11.5" and 12.7" barrel versions?

This listing is for the 11.5" model. The 12.7" version features a pinned and welded muzzle device to meet the 16" overall length requirement for a non-NFA rifle. The 11.5" upper can be used in an AR pistol or SBR configuration depending on your lower receiver and local laws.

Will this work with standard AR-15 lower receivers?

The Brownells GAU-5A upper is designed for AR-15 compatible lower receivers. As always, verify your local and federal regulations regarding barrel length and overall rifle configuration before assembly.

Is the flash hider pinned and welded on the 11.5" model?

No. The 11.5" barrel has the flash hider installed but not pinned and welded. The pinned and welded configuration is only on the 12.7" model.