Ruger® AR-556® MPR 450 Bushmaster Proper Magazine Alignment Tech Tip

Published on November 22, 2021
Duration: 1:15

This guide details a critical technique for the Ruger AR-556 MPR chambered in .450 Bushmaster, focusing on proper magazine loading to prevent feeding malfunctions. Instruction from a Ruger official highlights how incorrect loading can cause the cartridge rim to snag on the bolt catch. By ensuring a small gap (approx. penny thickness) between the top round's rim and the magazine's rear wall, users can achieve reliable chambering and smooth operation.

Quick Summary

Proper magazine loading for the Ruger AR-556 MPR .450 Bushmaster prevents malfunctions by ensuring the top cartridge rim has a small gap (approx. penny thickness) from the rear magazine wall. This prevents the rim from catching the bolt catch during chambering, ensuring reliable feeding.

Chapters

  1. 00:00Introduction
  2. 00:16The Malfunction Issue
  3. 00:44The Solution

Frequently Asked Questions

How do I prevent feeding malfunctions with my Ruger AR-556 MPR in .450 Bushmaster?

Ensure proper magazine loading. Avoid tapping the magazine forcefully. The top cartridge rim should have a small gap, about the thickness of a penny, between it and the rear wall of the magazine to prevent it from catching the bolt catch.

What causes the .450 Bushmaster cartridge to jam in an AR-15 style rifle?

A common cause is the cartridge rim catching on the bolt catch. This often happens if the magazine is tapped too hard, misaligning the top round and allowing its rim to snag the bolt catch during chambering.

What is the correct magazine alignment for the .450 Bushmaster in an AR-556 MPR?

The top round should be seated forward in the magazine, leaving a gap between the cartridge rim and the rear wall of the magazine. This gap should be roughly the thickness of a US penny for optimal feeding.

Why is magazine alignment important for the .450 Bushmaster caliber?

The .450 Bushmaster's large rim diameter makes it susceptible to snagging the bolt catch if not properly aligned. Correct alignment ensures smooth feeding and prevents malfunctions, especially in single-stack magazine configurations common for this caliber.

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