Smyth Busters: Can Over-Lubrication Cause an AR-15 To Malfunction?

Published on April 6, 2021
Duration: 4:10

This guide, drawing on expertise from Brownells, addresses the myth of whether over-lubricating an AR-15 can cause malfunctions. Experts explain that while under-lubrication is typically worse, excessive oil can indeed lead to issues like increased bolt velocity, head thrust, and carbon buildup in the gas system, potentially causing the firearm to seize. Proper lubrication is key to reliable function.

Quick Summary

Over-lubrication can cause AR-15 malfunctions by attracting dirt and grit, increasing bolt velocity and head thrust, and leading to carbon buildup behind gas rings. While under-lubrication is often worse, excessive oil can impede function and potentially seize the firearm. Proper, moderate lubrication is essential.

Chapters

  1. 00:00Introduction to the Myth
  2. 00:15Dust and Dirt Accumulation
  3. 00:48Bolt Velocity and Head Thrust
  4. 01:55Carbon Buildup and Gas Rings
  5. 02:17Bolt-Action Malfunctions
  6. 03:01Conclusion and Myth Status

Frequently Asked Questions

Can over-lubricating an AR-15 cause it to malfunction?

Yes, over-lubrication can cause AR-15 malfunctions. Excess oil can attract dirt and grit, leading to issues. It can also increase bolt velocity and head thrust, and lubricant can carbonize behind gas rings, potentially seizing the rifle.

What are the main risks of over-lubricating a firearm?

The primary risks include attracting dust, dirt, and grit which can impede function. Extreme over-lubrication can increase bolt velocity and head thrust. Additionally, lubricant can carbonize in hot areas like behind gas rings, leading to malfunctions or seizure.

How does over-lubrication affect bolt velocity and head thrust in an AR-15?

A lubricated chamber reduces friction on the casing, allowing it to move rearward with greater force upon firing. This increased casing movement translates to higher bolt velocity and consequently, increased head thrust against the bolt face.

What role does carbon buildup play in malfunctions related to over-lubrication?

When excessive lubricant is present in hot areas like behind the gas rings of an AR-15's bolt carrier, it can break down and carbonize. This hardened carbon deposit can impede the movement of the gas rings, leading to malfunctions or the rifle seizing.

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