FN AR-15 M16 Barrel 18 Rifle Length 5.56mm
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FN America
Overview
The FN AR-15 M16 Barrel is an 18-inch, M4 profile barrel designed for optimal performance with 5.56 NATO ammunition. Featuring a rifle-length gas system with a .750 gas block diameter, this barrel is tailored for reliable cycling and accuracy, while its 1:8 twist rate provides versatility in stabilizing a range of bullet weights. This barrel is commonly found in builds that prioritize a rifle-length gas system and utilize 5.56 NATO caliber, making it a solid choice for precision and reliability.
Specifications
August 2026 on GunPartPicker
FN America FN AR-15 M16 Barrel 18 Rifle Length 5.56mm ranked #51 of the 298 barrels builders added on GunPartPicker in August 2026. Builders have been adding it to their builds on GunPartPicker since February 2026. All time, it ranks #40 of the 814 barrels builders have added. Builds with this barrel are nearly all chambered in 5.56 NATO, nearly all on rifle-length gas, and split between AR-10 (50%) and AR-15 (50%).
It was in stock most days in August 2026, and today 5 of the 7 retailers we track have it in stock. It dipped to $241.50 at KY Gun Company for a stretch in August 2026, well under its usual $279, so sales do come around. Buying today, the lowest price is $226.49 at Ammunition Depot, which matches the best price we saw in August.
Updated · from real builds on GunPartPicker · Prices checked · refreshed daily across 35 retailers
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Frequently Built With
The part most often added in each category by the 18 builds that include this one
Bravo Company Mfg Upper Receiver Assembly w/ Laser T-Markings, Hard Coated Anodized - 4-UR-M4
Breek Arms AR-15 Warhammer MOD2 Ambidextrous Charging Handle Black
Bravo Company M16 Bolt Carrier Group Black
WMD Guns AR-15 Gas Tube Nitromet Rifle
Griffin Armament MK2 Ambi Stripped AR-15 Lower Receiver - Ambidextrous Controls - Flared Magwell - Anodized Black - MK2AL
Spike's Tactical Crr Quad Rail AR-15 Handguard - 15"
Build Configuration Breakdown
Aggregated and anonymized data showing how builders use this product
PlatformBased on real build data showing which platform (AR-15, AR-10, AR-9) builders pair with this product.
Builds Featuring This Part
See all 3 →Builds in the community that include the Fn Ar-15 M16 Barrel 18 Rifle Length 5.56mm
| Build | Parts | Total |
|---|---|---|
 | 28 | $3331.46 |
 | 25 | $2938.88 |
 | 10 | $897.91 |
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