For the best barrel length for 5.56 performance, a longer barrel is preferable, with 20 inches being ideal as it aligns with the original design specifications of the 5.56 round, offering maximum muzzle velocity and effective range.
This is due to the extended barrel length allowing more time for the gunpowder to burn completely, thus converting more gas into forward thrust and delivering greater impact.
| Barrel Length | Muzzle Velocity | Max Range |
|---|---|---|
| 20 in | 3100 ft/sec | 600 yards |
| 18 in | 3050 ft/sec | 500 yards |
| 16 in | 2800 ft/sec | 500 yards |
| 14.5 in | 2750 ft/sec | 300 yards |
| 12.5 in | 2600 ft/sec | 200 yards |
| 10.5 in | 2500 ft/sec | 200 yards |
However, the concept of "best" extends beyond mere ballistics. A longer barrel can make the rifle more cumbersome and front-heavy, complicating offhand shooting and maneuverability in confined spaces like buildings or vehicles.
For more dynamic or close-quarters scenarios, shorter barrels, such as the 14.5-inch standard on the M4 carbine or even a 12.5-inch variant, might be more practical, balancing ease of handling with performance.
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Best Barrel Length For 5.56 General Recommendations
- A 16" barrel is frequently mentioned as a versatile option (Legal rifle barrel length), providing a good balance between velocity, range, weight, and maneuverability, making it a "jack of all trades" length.
- For home defense and short-range engagements, shorter barrels, particularly in the 10.3" to 11.5" range, are favored for their compactness and ease of maneuverability within confined spaces.
- Some users advocate for mid-lengths like 13.7" to 14.5" for a balance between compactness and ballistic performance. 14.5" pinned and welded muzzle device can meet the 16" overall barrel length legal requirement.
- Barrel lengths of 18" to 20" are suggested for those prioritizing long-range shooting and maximum ballistic performance.
AR15 barrel gas length is also a thing to consider
Recommendations for First-Time Buyers:
Stay with the 16" barrel length for simplicity, or buy 14.5" pinned and welded barrels
Home Defense Considerations
- There's a debate about the practicality of longer barrels (like 16") when paired with a suppressor for home defense, with some users expressing concerns about overall length and maneuverability.
- An 11.5" barrel length is often recommended for home defense due to its compactness and sufficient ballistic performance at close quarters. But you have to file NFA paper work.
Velocity and Ballistics
- Longer barrels provide better velocity and ballistic performance, which is essential for long-range shooting.
- Different barrel twist rates can affect ballistics relative to barrel length
- Shorter barrels are considered adequate for close to medium range and are easier to handle, especially in tight spaces.
Suppressor Use
The addition of a suppressor is a significant consideration, affecting the overall length and maneuverability of the firearm. Shorter barrels are generally preferred when planning to use a suppressor, especially for home defense scenarios. A 16" length barrel with a long suppressor can make the whole thing as long as 20 in".