Best Barrel Length For 5.56

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. 

AR15 Barrel Specifications
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

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  • 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

ar15 gas length

Recommendations for First-Time Buyers:

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Stay with the 16" barrel length for simplicity, or buy 14.5" pinned and welded barrels

Home Defense Considerations

geissele ar15 handguards
  • 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

best ar15 barrel twist rate
  • 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".

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