Measuring the barrel length of your AR-15 is crucial for several reasons, from ensuring compliance with legal regulations to understanding your rifle's ballistic performance. Whether you're a seasoned AR-15 owner or a newcomer, knowing how to accurately measure your barrel is essential. This guide will walk you through the process, clarifying common misconceptions and ensuring you get a precise measurement.
Why Measuring Barrel Length Matters
The length of your AR-15 barrel directly impacts several key factors:
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Velocity and Accuracy: Shorter barrels generally produce lower muzzle velocities and potentially less accurate shots, especially at longer ranges. Longer barrels allow for more complete powder burn, resulting in higher velocities and, often, improved accuracy.
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Legal Compliance: Barrel length is a critical factor in determining legal compliance with firearm regulations in your area. Failure to comply can result in serious legal consequences. Knowing your barrel length helps you ensure you're meeting all applicable laws.
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Parts Compatibility: When replacing or upgrading parts, knowing your barrel length ensures compatibility with other components, such as gas systems and handguards. An incorrect length can lead to malfunctions.
Methods for Measuring AR-15 Barrel Length
There are two primary ways to measure your AR-15 barrel length:
1. Measuring from the Bolt Face to the Muzzle
This is the most common and generally accepted method. Here's how to do it:
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Safety First: Always ensure your firearm is unloaded and clear of ammunition before handling.
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Gather Your Tools: You'll need a flexible measuring tape or a ruler. A flexible tape measure is often preferable for ease of use.
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Access the Bolt Face: Remove the upper receiver from the lower receiver. If your upper receiver has a forward assist, it might be helpful to remove it as well for easier access to the bolt face.
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Start at the Bolt Face: Place the end of your measuring tape or ruler at the bolt face (the rearmost part of the barrel that interacts with the bolt).
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Extend to the Muzzle: Extend the measuring tape or ruler to the very tip of the muzzle (the end of the barrel).
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Record the Measurement: Record the measurement in inches. This is your barrel length.
Important Note: This method measures the actual barrel length, excluding any threads or muzzle devices.
2. Measuring from the End of the Receiver to the Muzzle (Less Accurate)
This method is less precise because it incorporates the extension of the barrel inside the upper receiver. While it provides a general idea, it's not as accurate for determining ballistic performance or verifying compliance with regulations.
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Follow Steps 1 & 2 from Method 1.
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Start at the Receiver: Position the end of your measuring tape or ruler at the end of the upper receiver where the barrel emerges.
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Extend to the Muzzle: Extend the tape measure to the muzzle.
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Record the Measurement: Record the measurement. This measurement will be longer than the actual barrel length.
Understanding Barrel Length Terminology
Common terms associated with AR-15 barrel lengths often cause confusion:
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Carbine Length: Typically refers to barrels around 14.5-16 inches.
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Mid-Length: Usually around 16-18 inches.
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Rifle Length: Generally indicates barrels 20 inches and longer.
These are broad classifications; there's a wide range of barrel lengths available.
Conclusion
Accurately measuring your AR-15 barrel length is a straightforward process but crucial for understanding your rifle's performance and ensuring legal compliance. By following the steps outlined above, you can confidently determine the exact length of your barrel and make informed decisions about upgrades, modifications, or any other relevant actions. Remember always to prioritize safety when handling firearms.
