Choosing the right barrel length for your AR-15 is a crucial decision impacting accuracy, ballistics, and overall performance. This in-depth comparison dives into the differences between 11.5" and 13.7" barrels, helping you decide which is best for your needs. We'll examine factors like ballistics, suppressor compatibility, legality, and practical applications.
Ballistic Performance: Range and Accuracy
The most significant difference between an 11.5" and a 13.7" barrel lies in their ballistic performance. A longer barrel allows for more complete powder burn, resulting in higher muzzle velocity and a flatter trajectory.
Muzzle Velocity and Energy
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11.5" Barrel: Generally delivers lower muzzle velocity and less kinetic energy compared to a 13.7" barrel. This translates to a shorter effective range and potentially less stopping power. The shorter barrel also leads to a more dramatic bullet drop at longer ranges.
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13.7" Barrel: Offers noticeably higher muzzle velocity and kinetic energy, extending the effective range and improving accuracy at longer distances. The increased velocity also leads to a flatter trajectory, making long-range shots easier to execute.
| Barrel Length | Muzzle Velocity (5.56 NATO) | Estimated Effective Range |
|---|---|---|
| 11.5" | ~2300 fps (approximate, varies by ammo) | ~200 yards |
| 13.7" | ~2500 fps (approximate, varies by ammo) | ~300 yards |
Note: These are estimates and can vary significantly based on ammunition type, barrel twist rate, and other factors.
Accuracy
While both barrel lengths are capable of acceptable accuracy, the 13.7" generally provides a slight edge, particularly at longer ranges. The increased powder burn and higher velocity contribute to improved grouping. However, the difference might be negligible for many shooters at closer ranges.
Suppressor Considerations: A Key Differentiator
The 11.5" and 13.7" barrels differ significantly in their suitability for suppressors.
11.5" Barrel and Suppressors
An 11.5" barrel with a suppressor attached often results in a configuration that is shorter than the legal minimum overall length for a rifle under the National Firearms Act (NFA). This can lead to legal complications if not carefully planned.
13.7" Barrel and Suppressors
A 13.7" barrel paired with a permanently pinned and welded muzzle device (like a flash hider or brake) can bring the overall length above the legal minimum, even with a suppressor attached. This allows for legal NFA compliance while enjoying the benefits of suppressed shooting. This is a popular choice for those wanting a shorter, more maneuverable rifle while still maintaining legal compliance with a suppressor.
Important Note: Always consult with legal counsel and understand the NFA regulations in your area before adding suppressors or permanently modifying your firearm.
Legal Aspects: NFA Compliance
As mentioned above, NFA compliance is a critical concern when choosing between these barrel lengths, particularly when using a suppressor. The overall length of the firearm with any permanently attached items (like a muzzle device) must meet legal requirements. Improper configurations can lead to serious legal penalties.
Practical Applications: Choosing the Right Barrel
The ideal barrel length depends heavily on intended use.
11.5" Barrel Applications
- Close-quarters combat (CQB): The shorter length makes it highly maneuverable in tight spaces.
- Home defense: Its compact size facilitates easier handling within a home environment.
- Vehicle-mounted: Its smaller size allows for easier storage and use in vehicles.
13.7" Barrel Applications
- Mid-range engagements: Provides improved accuracy and range compared to the 11.5".
- Law enforcement/military applications: Its increased performance makes it suitable for various operational scenarios.
- Hunting (with appropriate ammunition): Offers more stopping power and better range compared to the 11.5".
Conclusion: The Verdict
The "best" barrel length—11.5" or 13.7"—depends entirely on your individual needs and priorities. The 11.5" excels in close-quarters scenarios due to its maneuverability, but sacrifices some accuracy and range. The 13.7" offers better accuracy and range, making it suitable for mid-range shooting and legal suppressor use with a pinned and welded muzzle device, but compromises on maneuverability. Careful consideration of your intended use, legal requirements, and ballistic performance will guide you to the optimal choice for your specific AR-15 build.