Looking to build a compact, reliable 9mm AR pistol or SBR? The AR9 4.5″ 9mm barrel is a critical component for that project. This barrel is machined from 416 stainless steel and finished in a durable Radio Active color, offering both performance and a unique visual flair. It’s designed for builders who demand quality AR-15 parts and want a barrel that delivers consistent accuracy in a short, maneuverable package.
Key Features
- Machined from 416 stainless steel for excellent strength and bore life.
- Short 4.5-inch length ideal for ultra-compact 9mm AR pistol builds.
- 1:10 twist rate optimized for stabilizing a wide range of 9mm bullet weights.
- 1/2×36 thread pattern allows for direct attachment of common 9mm muzzle devices.
- Radio Active finish provides a distinctive look and added corrosion resistance.
Built For
This barrel is perfect for the DIY enthusiast building a dedicated 9mm AR platform for home defense, competition, or as a compact range toy. Its short length makes it an ideal choice for a backpack firearm or a suppressor host when paired with the appropriate muzzle device and tax stamp.
Specifications
- Caliber: 9mm Luger (9×19)
- Material: 416 Stainless Steel
- Length: 4.5 Inches
- Twist Rate: 1:10
- Thread Pitch: 1/2×36
- Finish: Radio Active
FAQ
Will this barrel work with my Glock-magazine AR-9 lower?
Yes, this barrel is compatible with most AR-9 platforms, including those designed for Glock-style magazines. Always confirm compatibility with your specific upper receiver and bolt carrier group.
What kind of muzzle device can I use?
The 1/2×36 thread is standard for many 9mm compensators, flash hiders, and thread protectors. You can also find adapters to mount .22 caliber or larger devices if needed.


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