Understanding the Legal Definition of Overall Length
The Basics
To correctly measure the overall length of your AR pistol, you must first understand what constitutes “overall length” in the eyes of the law. The Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) has specific guidelines defining what components of a firearm are included in the OAL measurement. The focus is on what is legally relevant for the purposes of firearm classification.
Key Components Included
The key point to remember is that the OAL measurement is designed to determine whether a firearm meets the definition of a pistol, a short-barreled rifle (SBR), or an other category firearm. These determinations have different legal implications.
The OAL measurement *must* include the following essential components:
- The Receiver: Both the upper and lower receiver components must be connected during the measurement. They form the core of the firearm, and their combined length is a standard starting point.
- The Barrel: The barrel is a critical component. You should measure the barrel from the tip of the muzzle, which is where the bullet exits the barrel, to the rear of the barrel where it threads into the receiver.
- Muzzle Device (If Permanently Attached): Muzzle devices, such as flash hiders, compensators, or suppressors, are included in the OAL measurement *only if they are permanently attached*. A permanently attached muzzle device is one that is attached to the barrel via methods like welding, soldering, or pinning, and is not easily removed without damaging the firearm. The key consideration here is whether the attachment is readily reversible.
Components Excluded
Conversely, certain components are specifically *excluded* from the OAL measurement. These exclusions are critical to understand, as they often define a firearm’s legal status and features.
- Magazine: The magazine, which feeds ammunition into the firearm, is not included in the OAL measurement.
- Stock or Brace When “in the Folded or Collapsed Position”: This is perhaps the most critical aspect for AR pistols. The overall length is to be measured with the stock or brace *in the folded or collapsed position, if the arm is equipped with a folding or collapsing stock or brace*. This is generally the position where the firearm takes up the least amount of space. This is critical because if the stock or brace is capable of being folded or collapsed, the weapon’s OAL is measured while folded or collapsed, and this is how you determine legal compliance.
The ATF’s guidelines regarding OAL are subject to change, and it’s vital to stay updated with the latest rulings and interpretations.
Tools and Materials You’ll Need
Essential Tools
To accurately measure the overall length of your AR pistol, gather the following tools and materials:
- A Ruler or Measuring Tape: Choose a ruler or tape measure that is rigid and easy to read. The best choice will depend on the parts of your firearm. Be sure to use a measuring device that accurately reflects the inches.
- A Solid Surface: You’ll need a flat, level surface on which to place your AR pistol. A table, workbench, or other stable surface is ideal. Make sure this surface provides a solid base and will not cause inaccuracies in your measurements.
- A Pen or Pencil and Paper: Always record your measurements, which allows you to cross-reference the data and avoid errors.
Optional Tools
- A Level: A small level can help ensure that your firearm is perfectly straight during measurement, minimizing any potential measurement errors caused by tilt.
- A Small Block: A small block placed against the muzzle or barrel end can act as a stop and help you get more accurate measurements.
Step-by-Step Guide to Measuring OAL
Safety First
Now, let’s get into the actual measurement process.
Before handling your AR pistol, always prioritize safety. Ensure that the firearm is unloaded by visually and physically inspecting the chamber and magazine well. It is always wise to operate in a safe environment where you can handle the firearm responsibly.
Preparing the Firearm
The best method for measuring the overall length of your AR pistol begins with your firearm in a safe state. Remove the magazine from the firearm, even if it is empty. Ensure that there is no ammunition in the chamber or magazine. This step is crucial for safety and ensures that you aren’t including the magazine in the measurement.
Measuring the Barrel Length
Next, you must determine the length of the barrel. Position the firearm with the muzzle end facing away from you.
- If the muzzle device is *not* permanently attached, carefully measure from the tip of the muzzle to the rear end of the barrel where it threads into the upper receiver.
- If the muzzle device *is* permanently attached, include it in the measurement. Measure from the tip of the muzzle device to the rear of the barrel, where it threads into the upper receiver. The length of the muzzle device will be a part of the barrel length.
Record the barrel length on your paper. Double-check your measurement to ensure accuracy.
Measuring the Receiver, Buffer Tube, and Brace Length
Position the AR pistol with the muzzle end against the edge of a table. This is a consistent reference point from which to measure. Place the ruler or tape measure along the entire length of the firearm, from the front of the receiver, to the end of the brace or buffer tube, ensuring that it is in the folded/collapsed position (if possible) if a folding or collapsing stock or brace is present.
- Measure from the base of the receiver to the end of the brace or buffer tube in its folded/collapsed position.
Record this second measurement.
Calculating the Overall Length
Now, it is time to add the two measurements.
- Add the barrel length (from the Barrel Length Step) to the total length of the receiver, buffer tube, and brace or buffer tube (from the previous step).
The result is the overall length (OAL) of your AR pistol.
Accuracy Check
Review your work. Double-check all measurements and calculations. Confirm that the firearm was in the correct configuration for measurement, especially if it has a folding or collapsing stock or brace. Compare your calculated OAL to any relevant legal thresholds for your location. This step is essential to ensure that your measurement is correct.
Special Considerations and Circumstances
Muzzle Devices
Several unique aspects of AR pistol construction can significantly influence OAL measurements. As mentioned earlier, permanently attached muzzle devices are included in the barrel length measurement. Be certain that the attachment meets the ATF’s definition of “permanent,” typically involving welding, pinning, or soldering. If the muzzle device is easily removable, it is *not* permanently attached and should *not* be included.
Folding Stocks/Braces
The most relevant consideration for AR pistols concerns folding stocks or braces. If the firearm is equipped with a folding stock or brace, the OAL *must* be measured with the stock or brace in the folded or collapsed position. This ensures that you are measuring the firearm in its most compact configuration.
Aftermarket Components
Upgrading or modifying your AR pistol with aftermarket components can affect its OAL and, by extension, its legal status. Pay close attention to any parts that add length to the firearm. If these additions push the firearm into a different legal category, this will affect compliance.
Federal and State Laws
Firearm laws vary greatly by state and locality. Always be aware of and comply with both federal and state regulations. Some states may have stricter definitions of OAL or specific requirements regarding AR pistols, braces, and other features.
Common Mistakes to Avoid
Incorrect Procedures
Avoiding common measurement errors will help ensure your measurements are correct.
- Measuring with a Loaded Magazine: Never measure a firearm with a loaded magazine. It is dangerous and could invalidate your measurement.
- Not Measuring from the Correct Points: Ensure that you are measuring from the muzzle’s tip to the correct points on the receiver, brace or buffer tube.
- Incorrectly Measuring a Muzzle Device: Ensure that you know whether your muzzle device is permanently attached.
- Not Understanding the “Folded or Collapsed” Position: Measure the firearm in its folded or collapsed position (if applicable), as this is the key to legal compliance in many circumstances.
Conclusion
Accurately measuring the overall length of your AR pistol is a vital step in ensuring that you are compliant with federal, state, and local laws. By following the steps outlined in this guide and being aware of the special considerations, you can confidently determine your firearm’s OAL. Always prioritize safety and double-check your measurements.
It is important to remember that this guide provides general information and is not a substitute for legal advice. If you have any specific questions or concerns regarding firearm laws, it is always recommended to consult with a qualified legal professional.
In the constantly evolving landscape of firearms legislation, staying informed is critical. This guide provides a foundation for accurately measuring your AR pistol’s overall length. By taking the time to understand the relevant laws, using the proper tools, and following these simple steps, you can help ensure that you enjoy your AR pistol responsibly and legally. Double-check your measurements, be sure to consult with your local law enforcement and attorney, and always prioritize safety.
