Centurion MK12 18” Barrel Tested with MK262 and Other 77gr Loads

Published on January 22, 2026
Duration: 16:50

This video provides an in-depth review and testing of the Centurion Arms MK12 18-inch 5.56 NATO barrel. Preston Moore, demonstrating high expertise, meticulously inspects and tests the barrel with various 77gr loads, including MK262. The results highlight the barrel's accuracy potential, particularly with MK262, and offer valuable data for AR-15 builders and precision shooters.

Quick Summary

The Centurion Arms MK12 18" barrel, made from 416R stainless steel with a 1:7 twist, performed best with Black Hills MK262 77gr ammunition, achieving 1.688 MOA and 2724 fps in 30-shot groups at 100 yards. Other tested loads included IMI Razor Core, Federal Gold Medal, and PMC X-Tac M855.

Chapters

  1. 00:00Introduction & Barrel Overview
  2. 00:22Technical Specifications
  3. 00:57Inspection & Gauging
  4. 03:01Borescope Inspection
  5. 04:19Range Testing Methodology
  6. 05:31Ammunition Performance Results

Frequently Asked Questions

What are the key specifications of the Centurion Arms MK12 18" barrel?

The Centurion Arms MK12 18" barrel is chambered in 5.56 NATO, features an 18-inch length, 1:7 twist rate, and is constructed from 416R stainless steel. It utilizes a rifle-length gas system and has 1/2x28 threads compatible with Ops Inc suppressors.

How did the Centurion Arms MK12 18" barrel perform with MK262 ammunition?

When tested with Black Hills MK262 77gr ammunition, the Centurion Arms MK12 18" barrel achieved a group size of 1.688 MOA and a muzzle velocity of 2724 fps over 30 shots at 100 yards.

What was the accuracy comparison between different 77gr loads tested with the Centurion Arms MK12 18" barrel?

The Centurion Arms MK12 18" barrel showed MK262 as the most accurate (1.688 MOA), followed by IMI Razor Core (1.731 MOA) and Federal Gold Medal (2.281 MOA). PMC X-Tac M855 was the least accurate at 3.180 MOA.

What is the significance of the 1:7 twist rate on the Centurion Arms MK12 18" barrel?

The 1:7 twist rate is optimized for stabilizing heavier projectiles, such as the 77gr rounds used in testing. This allows for better accuracy and performance with match-grade ammunition like MK262.

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