338 ARC Rifle Build
Caleb from Brownells introduces a new project: building an AR-15 chambered in .338 ARC. For those unfamiliar, the .338 ARC is a relatively new cartridge, similar in concept to the 300 Blackout but designed to fire a larger .338 projectile. It offers heavier subsonic performance, making it a hard-hitting option for hunters targeting hogs and similar game. Think of it as a scaled-down version of the 8.6 Blackout, but built for the AR-15 platform.
The advantage over 300 Blackout comes from its heavier bullet weight, which delivers more energy in subsonic applications while still fitting in a lightweight rifle setup.
AR-15 Lower Receiver Setup
The build starts with a standard AR-15 lower receiver that has already been assembled. Key components include:
This setup ensures a reliable and comfortable foundation for the upper assembly.
Optic and Mount Selection
For optics, Caleb selects the Trijicon Credo 1-8 variable optic, paired with a Midwest Industries Mark 2 mount. This mount provides strength and stability while remaining lightweight. The combination is well-suited for both close and extended ranges, making the rifle versatile for hunting and target shooting.
Handguard, Barrel, and Suppressor
The upper is built using a Midwest Industries Combat HD handguard, chosen for durability and robustness. The barrel is a Faxon Match Series chambered in .338 ARC, available in different lengths. Caleb’s build uses a shorter barrel for an SPR-style setup, though a 16-inch option is also available.
A Dead Air Nomad-X suppressor is installed, which is specifically designed for .338 caliber rounds. It helps keep the rifle quiet while reducing recoil, making it more enjoyable to shoot both at the range and in the field.
The muzzle device included is a Dead Air Zeno mount, which is suppressor-ready.
Gas System and Adjustability
A key feature of this build is the RifleSpeed adjustable gas block. Unlike traditional gas blocks, this one can be adjusted by hand without tools, allowing fine-tuning for both supersonic and subsonic ammunition. The clear tactile settings make it easy to use in the field.
This gas system is paired with a lightweight buffer system, ensuring smooth cycling. For shooters who run suppressed most of the time, this combination offers reliable performance across different loads.
Assembly Process
The build process includes:
- Greasing and installing the barrel extension into the upper receiver.
-
Torqueing the barrel nut using the Brownells armorer’s wrench.
-
Installing the RifleSpeed gas block and straight gas tube, secured with a roll pin.
-
Mounting the Midwest Industries handguard with proper torque specifications.
-
Shimming and aligning the muzzle device for correct suppressor attachment.
Each step ensures durability, proper fitment, and long-term reliability of the rifle.
Why Choose .338 ARC?
The .338 ARC cartridge offers unique advantages over traditional AR-15 calibers:
- Subsonic strength – hits harder than 300 Blackout in suppressed applications.
-
Hunting capability – excellent for hogs, coyotes, and medium game.
-
Lightweight platform – all the benefits of an AR-15 without needing a large-frame AR.
-
Versatility – works well suppressed or unsuppressed, with both subsonic and supersonic loads.
This makes it an ideal choice for hunters and shooters looking for more stopping power in a compact, AR-15 compatible caliber.
Final Thoughts
The AR-15 build in .338 ARC combines modern components, a powerful cartridge, and user-friendly features like the RifleSpeed adjustable gas block. It is optimized for hunters, tactical shooters, and enthusiasts who want a versatile and quiet rifle with excellent terminal performance.
Future range testing will provide more insights, but this build already demonstrates why the .338 ARC is generating buzz in the firearms community.
AR-15 build 338 ARC, 338 ARC AR-15, 338 ARC rifle, Brownells 338 ARC, Dead Air Nomad-X suppressor, RifleSpeed adjustable gas block, Faxon 338 ARC barrel, Trijicon Credo 1-8, Midwest Industries handguard, AR-15 hunting build, suppressed 338 ARC, subsonic 338 ARC, AR-15 hog hunting, Kung Fu Grip AR-15
