My FIRST AR10 Build | The " Sig MCX Spear XM7 at Home "

Published on March 8, 2023
Duration: 10:44

This guide details the process of building an AR-10 rifle inspired by the Sig MCX Spear XM7. It covers selecting components like receiver sets, barrels, handguards, and optics, with a focus on achieving the desired aesthetic and functional performance. Key steps include ensuring legal barrel length through pinning and welding, tuning the gas system with an adjustable block, and selecting appropriate buffer components for reliable cycling in .308.

Quick Summary

Building an AR-10 inspired by the Sig MCX Spear XM7 can be a cost-effective alternative to purchasing a factory rifle. Key components include an Aero Precision M5 receiver set, a 13.5-inch barrel pinned and welded to a muzzle device for legal 16-inch compliance, and an adjustable gas block for tuning. Proper buffer selection is crucial for reliable cycling in .308.

Chapters

  1. 00:00Introduction & Inspiration
  2. 00:37The "Sig Spear at Home" Build Revealed
  3. 01:03Building from Scratch vs. Buying Pre-Built
  4. 01:39Component Breakdown: Muzzle Device & Barrel
  5. 02:04Adjustable Gas Block & Pinned/Welded Barrel
  6. 02:35Handguard & Front Grip Selection
  7. 02:44Optic: Sig Tango MSR LPVO
  8. 03:28Receiver Set & Magazine Choice
  9. 03:44Grip & Stock: B5 Systems
  10. 03:59Charging Handle & Bolt Release
  11. 04:17Troubleshooting Feeding Issues
  12. 04:48The .308 Buffer Solution
  13. 05:45Performance & Sound Impressions
  14. 06:08Final Thoughts & Future Plans

Frequently Asked Questions

What caliber is the Sig MCX Spear XM7?

The official Sig MCX Spear XM7 is chambered in .227 Fury. However, this build replicates its appearance and function using the .308 Winchester caliber, which is a common and effective round for AR-10 platforms.

How can I legally build a short-barreled AR-10?

To legally build an AR-10 with a barrel shorter than 16 inches, you must pin and weld a muzzle device to the barrel. This combination must bring the total barrel length to 16 inches or more to comply with federal law.

What causes feeding issues in an AR-10 build?

Feeding issues in an AR-10 build, particularly with .308, can stem from incorrect buffer and buffer tube combinations. Using an AR-15 carbine buffer with a .308 spring in a carbine tube may not provide enough bolt travel. A .308 specific buffer is often required for proper cycling.

Is a .308 AR-10 build with a short barrel very loud?

While a short-barreled .308 AR-10 will be louder than a suppressed or longer-barreled rifle, this build's owner found it surprisingly manageable. With a muzzle brake, it was described as sounding quieter than a Springfield M1A.

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