Bad AR Parts

Published on December 19, 2019
Duration: 6:50

This video from School of the American Rifle showcases several problematic AR-15 components submitted by viewers. It highlights issues like bolt separation at the cam pin hole, case head separation in a 9mm barrel, a broken upper receiver due to improper tool use, a damaged barrel from attempting to remove a front sight base, a malfunctioning nickel boron bolt carrier group, and a barrel with a pin drilled into the bore. The instructor emphasizes the educational value of these failures for future classes and promises follow-up videos on diagnosis and repair techniques.

Quick Summary

School of the American Rifle highlights common AR-15 part failures, including bolt separation at the cam pin hole and case head separation in 9mm barrels. Improper tool use can break upper receivers, and aggressive removal of front sight bases can damage barrels and taper pins. Malfunctioning bolt carrier groups and barrels with drilled pin holes are also discussed.

Chapters

  1. 00:00Introduction: Bad AR Parts
  2. 00:10Bolt Separation at Cam Pin Hole
  3. 00:299mm Blowback Barrel Case Head Separation
  4. 01:05Broken Upper Receiver & Index Pin Damage
  5. 01:44Damaged Barrel from Front Sight Base Removal
  6. 02:21Mushroomed Taper Pins
  7. 03:00Malfunctioning Nickel Boron BCG
  8. 03:44Barrel with Pin Drilled into Bore
  9. 04:30Borescope Inspection of Damaged Barrel
  10. 06:09Visualizing the Pin Hole in the Bore
  11. 06:41Conclusion & Follow-up Videos

Frequently Asked Questions

What are common failure points for AR-15 bolts?

A critical failure point for AR-15 bolts is separation at the cam pin hole. This can occur due to manufacturing defects or extreme stress, leading to violent failure and rendering the firearm inoperable and potentially unsafe.

What causes case head separation in AR-15 barrels?

Case head separation in AR-15 barrels, particularly in 9mm blowback systems, can happen when the chamber is too long or worn, or due to improper ammunition. This leaves the brass casing stuck in the chamber, preventing further cycling.

How can an AR-15 upper receiver be broken during assembly or disassembly?

An AR-15 upper receiver can be broken by using incorrect tools, especially when dealing with seized barrel nuts or muzzle devices. Applying excessive force or leverage improperly can crack or damage the receiver itself or its critical alignment features.

What are the risks of improperly removing a front sight base on an AR-15 barrel?

Improperly removing a front sight base, such as using grinders or excessive force on taper pins, can severely damage the barrel. This can include gouging the barrel's surface, mushrooming taper pins, and even compromising the barrel's integrity or accuracy.

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