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Ar-15 Modern Series Barrels 9mm - Ar-15 Modern Series 5.5 Barrel
Our editorial team reviews specifications, product data, and field-use information to keep pages accurate.
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SKU: 915000088
Overview
Built for 9mm AR-15 setups, this 4.5-inch barrel is intended for shooters assembling a compact pistol-caliber platform with standard mil-spec uppers or dedicated 9mm upper options. It is machined from 4150 Chrome Moly Vanadium steel and finished with QPQ corrosion resistance, with 1/2-28 x .400 full profile threads for added suppressor mounting flexibility. The design supports both Colt/Rock River and Glock-style builds, but it does require the correct magwell conversion or a dedicated 9mm lower depending on the magazine system. An integrated feed ramp and blowback operation round out a straightforward option for a purpose-built 9mm AR configuration.
Why Hunters Choose the Ballistic Advantage
9mm Chambered
Barrel for AR-15 Modern Series
Machined From
4150 Chrome Moly Vanadium steel
Qpq Corrosion
Resistant finish included
Compatible Colt/rr
Colt/RR and Glock style AR
Works Standard
Standard mil-spec uppers
Key Features
- 9mm chambered 4.5-inch Modern Series barrel for AR-15 platform builds.
- Machined from 4150 Chrome Moly Vanadium steel.
- QPQ corrosion-resistant finish.
- 1/2-28 x .400 full profile threads.
- Compatible with Colt/RR and Glock style AR builds.
- Works with standard mil-spec uppers and dedicated 9mm upper options.
- Integrated feed ramp included.
Best Used For
- Users building a 9mm AR15 with Colt/Rock River style magwell conversion and UZI magazines
- Shooters planning a dedicated 9mm AR setup with Glock magazines and a compatible lower
- Builders wanting a compact 4.5-inch barrel for a modern-series 9mm AR configuration
- Owners of standard mil-spec uppers seeking a 9mm barrel with integrated feed ramp
- Users considering suppressor threading options in 1/2x28 or 1/2x36 configurations
Specifications
| Barrel Length | 4.5 inch |
|---|---|
| Blade Finish | QPQ Corrosion Resistant Finish |
| Caliber | 9mm |
| Compatibility | Colt/RR and Glock style AR builds |
| Feed Ramp | Integrated feed ramp |
| Gas Block Required | No |
| Gas Tube Required | No |
| Magwell Conversion Required | Unique magwell conversion (Colt/Rock River style) with UZI mags or a dedicated 9mm lower with Glock mags |
| Material | 4150 Chrome Moly Vanadium steel |
| Operating System | Blowback |
| Thread Pattern | 1/2-28 x .400 full profile threads |
| Threaded | 1/2x28 or 1/2x36 |
| Upper Compatibility | Standard mil-spec uppers |
Pros
- 9mm chambered barrel for AR-15 Modern Series builds
- Machined from 4150 Chrome Moly Vanadium steel
- QPQ corrosion resistant finish included
- Compatible with Colt/RR and Glock style AR builds
- Works with standard mil-spec uppers
- Threaded 1/2-28 x .400 full profile for suppressor versatility
Considerations & Trade-offs
- This 9mm barrel is intended for specific AR build configurations, so compatibility depends on using the correct upper and lower setup rather than a universal drop-in fit.
- It requires a unique magwell conversion with UZI mags or a dedicated 9mm lower with Glock mags, which adds setup considerations beyond a standard AR build.
- The 4.5 inch length is compact, but that format may not suit users looking for a longer barrel profile.
- Threading is provided in 1/2-28 x .400 full profile, so suppressor or muzzle-device selection should be matched to that thread pattern.
Suggested Comparisons
- AR-15 9mm barrels
- Dedicated 9mm AR upper receivers
- AR-15 magwell conversion kits
- Suppressor-ready muzzle devices
Suggested Accessories
- AR-15 upper receiver
- Magwell conversion kit
- Suppressor
- Thread protector
Frequently Asked Questions
What AR-15 setups is this 9mm barrel designed to work with?
It is designed for both Colt/Rock River style and Glock style AR builds. The product data also says it is compatible with standard mil-spec uppers, and that there are numerous dedicated 9mm upper options that work.
Does this barrel require a gas block or gas tube?
No. The product description says 9mm on an AR-15 platform operates by blowback and does not need a gas block or gas tube.
What lower or magazine setup is required?
The product data says it requires a unique magwell conversion for Colt/Rock River style use with UZI mags, or a dedicated 9mm lower with Glock mags.
What thread options are listed for this barrel?
The description lists 1/2-28 x .400 full profile threads, and also says it is threaded 1/2x28 or 1/2x36 for suppressor versatility.
What material and finish are specified?
The barrel is machined from 4150 Chrome Moly Vanadium steel and has a QPQ corrosion resistant finish.