LMT SPECWAR 12.5” Barrel Tested: Inspection, Borescope, and 30-Shot Groups

Published on February 18, 2026
Duration: 8:05

This expert review by Preston Moore details a comprehensive inspection and ballistic testing of the LMT 12.5" DI barrel in 5.56 NATO. The analysis includes borescope examination of the bore, chamber, and rifling, alongside detailed group testing with various ammunition types. The instructor highlights performance metrics like muzzle velocity and A-ZED scores, offering valuable insights for firearm enthusiasts and builders considering this barrel.

Quick Summary

The LMT 12.5" DI 5.56 NATO barrel features a chrome-lined bore, 1:7 twist, and mid-length gas system. Borescope inspection revealed minor imperfections. Ballistic testing showed moderate accuracy and velocities generally slower than comparable LMT piston barrels, with a 30-shot group of 2.372 MOA using 77gr SMK and an A-ZED of 256 yards.

Chapters

  1. 00:02LMT 12.5" DI Barrel Introduction
  2. 00:16Barrel Extension and DI Differences
  3. 00:35Inspection Gauging and Measurements
  4. 00:53Borescope Inspection of the Barrel
  5. 01:32Chrome Rough Spots and Blemishes
  6. 02:12Gas Port and Crown Inspection
  7. 02:55100-Yard Group Shooting with LMT
  8. 03:32Velocity and Group Size Data
  9. 04:17A-ZED Score and Performance Analysis
  10. 05:02ADI World Class Ammo Testing
  11. 05:33ADI World Class Results and Comparison
  12. 06:16PMC X-Tac M855 Testing
  13. 06:45PMC M855 Results and Barrel Comparison
  14. 07:16Group Size and Final Ranking

Frequently Asked Questions

What are the key specifications of the LMT 12.5" DI barrel?

The LMT 12.5" DI barrel features a chrome-lined bore, 5.56 NATO chamber, 1:7 twist rate, and a mid-length gas system. It utilizes a direct impingement action type.

How did the LMT 12.5" DI barrel perform in ballistic testing?

In testing with Federal Gold Medal 77gr SMK, the barrel averaged 2143 fps with a 30-shot group size of 2.372 MOA (256 yards A-ZED). With PMC M855, velocity SD was 18 fps and extreme spread 79 fps, with a 3.131 MOA group.

What were the findings from the borescope inspection of the LMT 12.5" DI barrel?

The borescope revealed minor imperfections including abrasion marks in the throat, some rough spots on the chrome lining, and a slightly rough crown. Fouling from factory test fire was also noted.

How does the LMT 12.5" DI barrel compare to other LMT barrels?

Compared to LMT piston barrels of similar or shorter lengths, the 12.5" DI barrel exhibited slower muzzle velocities. Its accuracy rankings were also generally lower than LMT piston models in the same tests.

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