SOFR Upper 8.2" 300BO (Suppressor Optimized) – 7.5" Hard-Line MLOK® Rail System - Cerakote

Overt Industries

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Overt Industries SOFR - 8.2" 300 Blackout Suppressor Optimized Fighting Rifle Upper – Suppressor Optimized

  • Overt Industries 8.2" 300 BLACKOUT SOB (Suppressor Optimized Barrel)
  • Overt Industries Thermal Fit Upper Receiver
  • Overt Industries Nitrided Steel Gas Block & Fighting Rifle Melonite Gas Tube
  • Overt Industries 7.5"" Hard-Line MLOK® Rail System - Cerakote Finish 


Assembly Process

This Upper Receiver assembly was properly assembled using Aeroshell 64 on the barrel extension and barrel nut after the threads were properly seasoned. The barrel was also properly dimpled using a BRD Engineering Pro Jig and the gas block set screws were tightened using Rocksett for maximum reliability at high temperatures. The handguard was assembled using Loctite 242 on the rail mounting bolts.


Component Specifications (Please Read)

Barrel Specifications

Introducing the Overt Industries 8.2" 300 Blackout AR-15 Suppressor Optimized Barrel (SOB)

Shooting a suppressed rifle offers many advantages to the end user, such as enhanced signature management, improved recoil impulse, and decibel reduction. However, suppressing a gas impingement AR15 does create some disadvantages due to the increased gas blowback that most suppressors create. The Overt Industries SOB Barrel line solves these issues and offers a reduced barrel gas port diameter that is optimized for the increase in gas blow back. This results in less gas in the face of the end user and improving felt recoil and the need for additional adjustable gas system components.

Gas Port Diameter = 0.086" 

Our requirement for our 300 Blackout SOB was for optimal gassing and reliability for Subsonic Suppressed and Supersonic Suppressed/Unsuppressed configurations. The 0.086" gas port met our requirement with maintaining reliability and offering very soft recoil impulse when shooting subsonic ammunition suppressed, which we feel is the primary use case of a short barrel 300 Blackout AR15. Optimizing the gas system for this end use does result in losing the reliability of shooting subsonic ammunition without a suppressor. However, we feel there is zero practicality in shooting subsonic 300 Blackout without a suppressor. 

For this barrel we highly recommend starting with a standard 3oz carbine buffer & spring (or Sprinco white) for shooting subsonic ammunition suppressed. Shooting Supersonic ammo suppressed will allow for a H/H2 buffer & Sprinco blue. We developed these barrels around a traditional baffle stack suppressor, therefore some of the flow through suppressors may require a reduced power buffer spring when shooting subsonic ammo suppressed.

Unlike other companies, we publicly disclose our gas port diameter so you, the end user knows exactly what they are purchasing. As shooters, we were frustrated when companies refused to disclose their gas port diameters and we were left to purchase barrels hoping for a desired result.  

  1. Unparalleled Suppressor Compatibility: Our barrel is designed with subsonic ammunition and suppressor use in mind, featuring a conservative gas port size that provides a soft, flat shooting recoil impulse and less gas to the end user's face with their suppressor. We recommend a Standard Carbine 17-7 Steel Spring or Sprinco White and a Standard (3oz) Buffer or H1 Buffer depending on your specific suppressor and ammunition. Keep in mind this barrel is intended for suppressor use and in most cases, will not reliability run subsonic ammunition unsuppressed. 
  2. Premium Materials: Crafted from high-quality, precision-machined stainless steel, our barrel is built for hard use. It's corrosion-resistant, durable, and capable of withstanding the rigors of extended use. 
  3. Precise Rifling: The barrel boasts precise 1:7 twist rifling, optimizing stability and accuracy with a wide range of bullet weights. Whether you're shooting supersonic rounds or heavier subsonic ammunition, expect exceptional accuracy downrange.
  4. Optimized Length: At 8.2 inches, this barrel strikes the perfect balance which allow the end user the flexibility of a short weapon system chambered in 300 Blackout without sacrificing performance or ballistics. ALL NFA RULES APPLY!
  5. Overt Industries Reliability: Overt Industries is known for its commitment to quality and innovation. We 100% QC every SOB barrel and ensure that the gas port diameter is within 0.001" of our specification of 0.086". Our suppressor-optimized barrel is no exception, embodying our Hard Use - Zero Sacrifice Ethos. 

Our barrels include one gas block set screw dimple located directly under the gas port for enhanced durability and compatibility with industry standard gas blocks. 

Length  8.2″
Weight 17.7 Oz
Material 4150 CMV
Profile Heavy
Caliber 300 Blackout
Twist 1/7
Muzzle Device Thread 5/8x24
Gas Block Journal 0.750"
Gas System Pistol
Finish Nitride


Note this barrel is optimized for suppressor use, shooting without a suppressor or with remanufactured or low quality ammunition may result in varying performance. NFA Rules Apply. 


Overt Industries Hard-Line MLOK® Rail System 

The Hard-Line MLOK® Rail System was designed with an emphasis on Rigidity, Ruggedness, and Simplicity. 100% Made in the USA, the Hard-Line MLOK® Rail System utilizes a Three Point Mounting System to ensure that the handguard clamps securely to the barrel nut without the possibility of unwanted rotation.

Machined from American sourced 7075 T-6 extruded aluminum, the Hard-Line MLOK® Rail System offers increased strength, rigidity and reduces overall handguard flex by removing often unused MLOK® sections in order to enhance the structure of the rail system. The increase in handguard rigidity reduces handguard flex resulting in a stronger mounting structure for Laser Aiming Devices. We also integrated chamfered serrations to the exterior of the rail system in order to provide maximum grip friction to the end user. 


  • Free float design
  • Chamfered Serrations and Leading Edges 
  • Ambidextrous Integrated QD Sockets 
  • 7-Sided M-LOK®
  • 2" M-LOK® Attachment
  • American sourced 7075 T-6 extruded aluminum
  • 4140 Steel Barrel Nut
  • MIL-A-8625 Type III Class 2 Anodizing