This AR9 4.5″ 9mm barrel is built for compact pistol-caliber carbine (PCC) builds where reliability and straightforward installation matter. It’s a solid choice for builders looking for a short, durable barrel at a practical price point. We added this model to our catalog in summer 2025 based on consistent positive feedback from other retailers and builders. On our scale, it weighs 4.2 oz.
Stand-Out Features
- 416 Stainless Steel Construction: Provides a good balance of machinability and strength for a 9mm barrel at this price.
- Durable Black Finish: Our staff noted the coating held up through multiple cleaning cycles with Hoppes No. 9 solvent without degrading.
- Standard 1/2×28 Thread Pitch: Directly compatible with common 9mm muzzle devices, suppressors, and thread protectors.
- 4.5″ Length: Designed for ultra-compact AR9 builds, maintaining reliable function with proper buffer tuning.
- 1:10 Twist Rate: A standard, proven twist rate for stabilizing common 115gr and 124gr 9mm ammunition.
Technical Data
| Caliber | 9mm Luger (9×19) |
| Barrel Length | 4.5 Inches |
| Twist Rate | 1:10 |
| Thread Pitch | 1/2×28 |
| Material | 416 Stainless Steel |
| Finish | Black |
| Weight (measured) | 4.2 oz |
| Chamber | 9mm |
Your Questions Answered
Will this barrel work with my Glock-magazine AR9 lower?
Yes. This is a standard AR9 barrel profile designed for use with dedicated 9mm AR lowers that accept Glock, Colt, or other magazine types. Compatibility is determined by your upper receiver and bolt, not the barrel itself.
Is the barrel extension included for headspacing?
Yes. The barrel ships with the barrel extension installed. You must properly headspace your bolt to the barrel using gauges for a safe build.
What muzzle devices fit the 1/2×28 threads?
Standard 1/2×28 muzzle devices for 9mm/.223/5.56 will fit. Ensure any device is rated for 9mm bore diameter. A 9mm-specific linear compensator or flash can is common for this barrel length.
✅ Plain brown box — no markings
✅ Not happy? Return within 30 days.
✅ Checkout secured with SSL encryption
✅ Domestic shipping — no customs
Reviews
There are no reviews yet.