Facebook Live Broadcast: AR-15 vs AR 308 Platforms

Published on January 19, 2017
Duration: 10:36

This video provides a detailed comparison between the AR-15 and AR-308 platforms, highlighting key differences in components and compatibility. It explains that while some lower receiver parts like springs, selectors, and trigger mechanisms (with heavy hammers/springs) can interchange, major components like the bolt carrier group, charging handle, and upper receiver are platform-specific due to size and cartridge differences. The discussion also covers barrel nut variations, muzzle device thread pitches (1/2x28 for AR-15, 5/8x24 for AR-308), gas block diameters, and the importance of matching receiver height (high vs. low profile) with handguards for proper alignment. It emphasizes that AR-308 components are less standardized than AR-15 parts, with DPMS pattern being the most common but variations like ArmaLite and DPMS Gen 2 requiring specific attention.

Quick Summary

AR-15 and AR-308 platforms differ significantly in size and component compatibility due to the larger .308 cartridge. While some lower receiver parts like springs, selectors, and triggers (with heavy hammers) can interchange, major components like the bolt carrier group and upper receiver are not compatible. Muzzle threads differ (1/2x28 for AR-15, 5/8x24 for AR-308), and AR-308 parts are less standardized than AR-15 parts.

Chapters

  1. 00:00Introduction: AR-308 vs AR-15
  2. 00:13Size Differences: AR-15 vs AR-308
  3. 00:37Interchangeable Small Parts
  4. 00:45Major Component Differences: BCG, Charging Handle
  5. 01:15Lower Receiver Parts Compatibility
  6. 01:34Lower Receiver Width Comparison
  7. 01:51Trigger Mechanisms: AR-15 vs AR-308
  8. 02:25Barrel and Muzzle Device Differences
  9. 02:43Gas System Compatibility
  10. 03:09Barrel Nut Differences
  11. 03:23Tools for Barrel Nuts
  12. 03:43Vice Clamping Devices
  13. 04:30Trigger Spring and Hammer Mass Considerations
  14. 04:56Buffer Systems: AR-15 vs AR-308
  15. 05:32Receiver Height: Low vs. High Profile
  16. 06:24DPMS Gen 2 AR-308 Specifics
  17. 07:09Extractor Compatibility
  18. 07:40Bolt Carrier Group Differences
  19. 08:28Magazine Compatibility Issues
  20. 09:01Non-DPMS AR-308 Patterns
  21. 09:34AR-308 Standardization vs. AR-15
  22. 09:55Conclusion and Future Topics

Frequently Asked Questions

Can I put an AR-308 upper receiver on an AR-15 lower receiver?

No, you cannot put an AR-308 upper receiver on an AR-15 lower receiver. The platforms are fundamentally different in size and component dimensions, primarily due to the larger .308 cartridge, making them incompatible for major assemblies like the upper and lower receivers.

What lower receiver parts are interchangeable between AR-15 and AR-308?

Many lower receiver parts can interchange between AR-15 and AR-308 platforms. This includes pivot pin and takedown pin springs, safety selector, magazine catch, and trigger mechanisms. However, for triggers, it's crucial that they have a heavy hammer and spring to reliably ignite the .308 cartridge.

What are the differences in muzzle device threads between AR-15 and AR-308?

The standard muzzle device thread pitch for an AR-15 is typically 1/2x28. For AR-308 platforms, the common thread pitch is 5/8x24. This difference requires specific muzzle devices for each platform.

Are AR-308 components standardized like AR-15 parts?

No, AR-308 components are significantly less standardized than AR-15 parts. While the DPMS pattern is common, variations exist between manufacturers and models (like DPMS Gen 2), meaning parts are not universally interchangeable across all AR-308 builds.

What is the difference between high and low profile AR-308 receivers?

High and low profile refer to the height of the AR-308 upper receiver. When choosing a handguard, it's important to match its height to the receiver's profile to ensure the top rails align perfectly, creating a continuous flat-top surface for optics and accessories.

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