12.5″ AR-15 Barrel — 4150 CMV, Nitride (5.56 NATO)
RBC (RifleBarrelCo) 12.5″ AR-15 Barrel — 4150 CMV, Parkerized, 1:7 Twist (5.56 NATO)
Barrel by RBC (RifleBarrelCo) · Available at Mid State Firearms
The RBC (RifleBarrelCo) 12.5″ AR-15 barrel is precision-machined from 4150 Chrome Moly Vanadium (CMV) steel and finished with a durable parkerized coating for long-lasting, corrosion-resistant performance. Designed with a 1:7 twist and a mid-length gas system, this barrel offers optimized dwell time, reliable cycling, and improved accuracy for a wide range of 5.56 NATO and .223 Remington loads.
Key Features
- Manufacturer: RBC (RifleBarrelCo) — sold by Mid State Firearms
- Barrel Length: 12.5″
- Material: 4150 Chrome Moly Vanadium (CMV)
- Finish: Parkerized
- Caliber / Chamber: 5.56 NATO (.223 compatible)
- Twist Rate: 1:7 — ideal for 55–77 gr projectiles
- Gas System: Mid-length for smoother gas dynamics
- Gas Journal: .750″ — pre-dimpled for secure gas block installation
- Muzzle Threads: 1/2×28 — fits standard muzzle devices
- Feed Ramps: M4-style for reliable feeding with Mil-Spec BCGs
Performance & Application
This 12.5″ RBC barrel is tuned for compact duty, RECCE, and suppressed configurations where balanced gas timing matters. The mid-length gas system reduces recoil impulse compared to carbine systems on short barrels, while the 1:7 twist stabilizes heavier bullets for improved accuracy at extended ranges.
Compatibility & Build Notes
- Fits standard AR-15 upper receivers and barrel nuts.
- Use with .750″ gas blocks and mid-length gas tubes; dimpled journal accommodates set-screw blocks.
- Professional installation and headspace check recommended for custom builds.
- Verify NFA/local laws for SBR/pistol vs rifle configurations before assembling.
Pair With These Mid State Firearms Components
- .750″ gas blocks & mounting hardware
- Free-float handguards and accessories
- More 5.56 / .223 barrels
- Contact Mid State Firearms for fitment help
Specifications
| Brand | RBC (RifleBarrelCo) |
| Barrel Length | 12.5″ |
| Material | 4150 CMV |
| Finish | Parkerized |
| Caliber / Chamber | 5.56 NATO / .223 Remington |
| Twist Rate | 1:7 |
| Gas System | Mid-length |
| Gas Journal | .750″ (pre-dimpled) |
| Muzzle Threads | 1/2×28 |
| Feed Ramps | M4 style |
Note: Product specs are provided by RBC (RifleBarrelCo). For installation or compatibility questions, contact Mid State Firearms.
-scaled-300x300.jpg "16' .223 Wylde 1:8 Mid-Length 4150 Lightweight Pencil Barrel, photo")
sound of freedom – This was a great set up. I loved being able to customize the set up. Only issue I had was my own fault as a newb to building these. I used a heavy barrel in a slim hand guard. It makes adding attachments tough with clearances. Hoping someday to also get an AR10 from here.