Top Mounted RMR vs 45 Degree Offset

Published on December 8, 2021
Duration: 11:32

This guide details techniques for transitioning between magnified optics and red dot sights on an AR-15 platform, comparing top-mounted RMRs and 45-degree offset mounts. The video, presented by a professional firearms reviewer, highlights ergonomic differences, transition times, and performance in various shooting scenarios, including weak-hand shooting and rapid fire drills. It concludes that offset mounts offer better ergonomics for sustained fire, while top-mounts excel in weak-hand transitions.

Quick Summary

45-degree offset red dot mounts on an AR-15 generally offer superior ergonomics and a more stable cheek weld for sustained fire compared to top-mounted optics. However, top-mounted optics are significantly easier to acquire when shooting from the non-dominant shoulder and can be faster for transitions from a red dot back to a magnified optic.

Chapters

  1. 00:00Introduction to Optic Mounting
  2. 00:25Custom AR-15 Build Overview
  3. 01:35Ergonomics and Transitions
  4. 02:09Durability and Protection
  5. 03:32Live Fire: Magnified to Red Dot
  6. 05:09Live Fire: Red Dot to Magnified
  7. 06:32Rapid Fire Drills
  8. 08:05Weak Hand Shooting
  9. 09:29Conclusion and Giveaway

Frequently Asked Questions

What are the pros and cons of top-mounted RMRs versus 45-degree offset red dots on an AR-15?

Top-mounted RMRs are easier for weak-hand shooting and red dot to magnified transitions. 45-degree offset mounts offer better ergonomics and cheek weld for sustained fire and magnified to red dot transitions, often resulting in slightly faster acquisition times in that specific scenario.

How does optic mounting affect transition times on an AR-15?

Transition times vary. Top-mounted optics can be faster from red dot to magnified due to eye relief alignment. Offset mounts are often faster from magnified to red dot because they allow for a tighter rotation while maintaining cheek weld.

Which AR-15 optic mounting solution is better for ergonomics?

The 45-degree offset mount generally provides superior ergonomics and a more stable cheek weld during sustained fire compared to the 'chin weld' often associated with top-mounted optics. This can lead to improved comfort and accuracy over longer shooting sessions.

Is a top-mounted RMR or a 45-degree offset mount better for weak-hand shooting on an AR-15?

Top-mounted optics are significantly easier to acquire and use when shooting from the non-dominant (weak) shoulder. This is because the optic naturally aligns with the eye in that position, whereas an offset mount can be more challenging to access quickly.

What are the key considerations when choosing between a top-mounted RMR and a 45-degree offset mount for an AR-15?

Consider your primary use case: duty/CQB might favor offset for ergonomics, while tactical/support roles might benefit from top-mount for weak-hand capability. Evaluate transition speed needs, comfort during sustained fire, and ease of use in unconventional positions.

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