AR9 4.5" 9mm 9×19 1:10 1/2×28 Barrel 416 Stainless Steel in Radio Active

If you’re building a compact AR-9 pistol or looking to upgrade your PCC, this AR9 4.5″ barrel is a core component you can trust. Designed for the popular 9mm AR platform, this barrel from Miami Shooters Supply delivers reliable performance in a short, maneuverable package ideal for close-quarters use and range fun. Machined from 416 stainless steel and finished in a distinctive Radio Active color, it combines durability with a unique look that stands out from standard black barrels.

Key Features

• Compact 4.5-inch length perfect for building an AR-9 pistol or a highly maneuverable PCC.
• Chambered in 9mm Luger (9×19), the most common and affordable pistol caliber for the AR-15 platform.
• Constructed from 416 stainless steel for excellent corrosion resistance and consistent bore life.
• 1:10 twist rate optimized for stabilizing a wide range of common 9mm bullet weights.
• 1/2×28 thread pitch allows for direct attachment of common muzzle devices, compensators, or thread protectors.
• Finished in a durable “Radio Active” colored coating for a unique aesthetic and added surface protection.

Built For

This barrel is ideal for the builder assembling a compact, fun-to-shoot AR-9 pistol for the range or home defense. It’s also a smart choice for competitors or enthusiasts who want a lightweight, short-barreled upper for practical shooting sports where quick handling is key.

Specifications

• Caliber: 9mm Luger (9×19)
• Material: 416 Stainless Steel
• Barrel Length: 4.5 Inches
• Twist Rate: 1:10
• Muzzle Thread: 1/2×28
• Finish: Radio Active Coating
• Platform: AR-15 / AR-9 (designed for use with dedicated 9mm AR lowers or adapters)

FAQ

Is this barrel compatible with my standard AR-15 lower?
No, this AR-15 part is chambered for 9mm and requires either a dedicated 9mm AR lower receiver or a magwell block adapter to function correctly with your existing lower.

What muzzle devices can I use with the 1/2×28 threads?
The 1/2×28 thread pattern is standard for 9mm and .223/5.56 barrels, so you can use many common flash hiders, compensators, or linear comps. Ensure any device is rated for 9mm bore diameter.