Brownells Ar-15 A2 Barrel Group 20'' 1-7 Twist, Rifle Gas

The Brownells AR-15 A2 Barrel Group is a rifle-length 20-inch barrel assembly built to mil-spec standards and ready for immediate installation on your AR platform rifle. This is serious hardware: manufactured by a US Government contractor and held to the same exacting tolerances as military-issue barrels. If you're building a precision rifle or upgrading an existing platform, this barrel group delivers the kind of consistent accuracy and reliability that comes from government-contract quality control—without the complexity of sourcing and fitting components separately.

The barrel itself is 4150 chrome moly steel with a hard chrome-lined bore applied over button rifling, a proven combination for accuracy, corrosion resistance, and longevity. Every barrel undergoes High Pressure Testing, followed by Magnetic Particle Inspection and gauging, so you know there are zero hidden flaws before it ships. The 1-7 twist is designed to stabilize heavier projectiles—62 grain and greater—while remaining versatile enough for standard 5.56x45mm NATO loads. Chamber and markings confirm mil-spec 5.56x45mm NATO specs.

Assembly convenience matters too. The slip ring, F-marked front sight base, and rifle-length handguard cap come pre-installed, so you can bolt this group directly to your upper receiver without hunting for pieces or fussing with alignment. The triangle handguard cap is the correct profile for 20-inch rifle-length barrels, not a generic fit. This is the kind of attention to detail—and speed to range—that separates a kit-built rifle from a finished one.

Key Features

• 20-inch barrel length—ideal for full rifle velocity and accuracy at distance
• 1-7 twist optimized for heavier 5.56x45mm projectiles
• 4150 chrome moly steel with hard chrome-lined bore for durability and corrosion resistance
• Government contractor manufacturing and mil-spec inspection standards
• High Pressure Tested and Magnetic Particle Inspected for zero defects
• Pre-installed F-marked front sight base, slip ring, and rifle-length triangle handguard cap—ready to bolt on
• 5.56x45mm NATO chamber

Specifications

Frequently Asked Questions

What AR-15 uppers will this barrel group fit?

This barrel group is designed for standard AR-15 upper receivers chambered in 5.56x45mm NATO. The F-marked front sight base and rifle-length profile are compatible with flat-top and carry-handle uppers. Verify your upper's threading and gas tube system match before purchase.

What projectile weights does the 1-7 twist stabilize?

The 1-7 twist is optimized for 62 grain and heavier 5.56x45mm projectiles. Lighter loads may still function, but this twist is specifically engineered for the heavier end of the spectrum.

What comes pre-installed on this barrel group?

The slip ring, F-Marked front sight base, and rifle-length triangle handguard cap are already fitted and ready to go. You simply install the assembly on your receiver—no additional fitting or alignment required.

How is this barrel tested and inspected?

Every barrel is High Pressure Tested and then undergoes Magnetic Particle Inspection and gauging to ensure zero defects meet mil-spec standards before shipment.