Free Shipping & Free Returns*

FREE SHIPPING on Over 250,000 Products

Enjoy free shipping during the holidays! Shop now and get Free Value Shipping on most orders over $49 to the contiguous 48 states, DC and to all U.S. Military APO/FPO/DPO addresses.

Enjoy Our Extended FREE RETURNS

We want to ensure that making a return is as easy as possible! With our Hassle-Free, Extended Holiday Returns, eligible orders placed from November 12, 2025 on will benefit from an extended return deadline (January 13, 2026 or 30 days after receipt of your order - whichever is later). We'll even cover the cost of return shipping. Learn more about our Return Policy.

Shopping Cart
Government Restriction Government Restriction
You May Also Like
Best Rated Magpul Industries PMAG GEN M3 AR-15/M16/M4 Rifle Magazine w/Capacity Window, .223 Rem/5.56x45mm NATO, 30 Round, Black, 1 Pack, Polymer, MGMPI556BLK-30RD
Magpul Industries PMAG GEN M3 AR-15/M16/M4 Rifle Magazine w/Capacity Window, .223 Rem/5.56x45mm NATO, 30 Round, Black, 1 Pack, Polymer, MGMPI556BLK-30RD
(42)
List: $17.95 $16.95 Save Up to $1.00
Best Rated Magpul Industries PMAG GEN M2 MOE AR-15/M16/M4 Rifle Magazine, .223 Rem/5.56x45mm NATO, 30 Round, Black, 1 Pack, Polymer, MGMPI571BLK-30RD
Magpul Industries PMAG GEN M2 MOE AR-15/M16/M4 Rifle Magazine, .223 Rem/5.56x45mm NATO, 30 Round, Black, 1 Pack, Polymer, MGMPI571BLK-30RD
(45)
List: $12.95 $11.95 Save Up to $1.00
Best Rated Magpul Industries PMAG GEN M3 AR-15/M16/M4 Rifle Magazine, .223 Rem/5.56x45mm NATO, 20 Round, Black, 1 Pack, Polymer, MAG560BLK-20RD
Magpul Industries PMAG GEN M3 AR-15/M16/M4 Rifle Magazine, .223 Rem/5.56x45mm NATO, 20 Round, Black, 1 Pack, Polymer, MAG560BLK-20RD
(18)
List: $14.95 $13.95 Save Up to $1.00
Best Rated Magpul Industries PMAG GEN M3 AR-15/M16/M4 Rifle Magazine w/Capacity Window, .223 Rem/5.56x45mm NATO, 30 Round, Coyote Tan, 1 Pack, Polymer, MAG556-MCT-30RD
Magpul Industries PMAG GEN M3 AR-15/M16/M4 Rifle Magazine w/Capacity Window, .223 Rem/5.56x45mm NATO, 30 Round, Coyote Tan, 1 Pack, Polymer, MAG556-MCT-30RD
(42)
List: $17.95 $16.95 Save Up to $1.00
Best Rated Magpul Industries PMAG GEN M3 AR-15/M16/M4 Rifle Magazine, .223 Remington, 40 Round, Black, 1 Pack, Polymer, MGMPI233BLK-40RD
Magpul Industries PMAG GEN M3 AR-15/M16/M4 Rifle Magazine, .223 Remington, 40 Round, Black, 1 Pack, Polymer, MGMPI233BLK-40RD
(10)
List: $22.95 $20.45 Save Up to 11%
Best Rated Magpul Industries PMAG GEN M2 MOE AR-15/M16/M4 Rifle Magazine w/Capacity Window, .223 Rem/5.56x45mm NATO, 30 Round, Black, 1 Pack, Polymer, MGMPI570BLK-30RD
Magpul Industries PMAG GEN M2 MOE AR-15/M16/M4 Rifle Magazine w/Capacity Window, .223 Rem/5.56x45mm NATO, 30 Round, Black, 1 Pack, Polymer, MGMPI570BLK-30RD
(11)
List: $15.95 $14.95 Save Up to $1.00
Amend2 Banana Mod-2 Magazine, AR-15/M4/M16, 5.56x45mm NATO/.223 Remington, 30 Round, Yellow, 1 Pack, Polymer, 556BANANA30-30RD
Amend2 Banana Mod-2 Magazine, AR-15/M4/M16, 5.56x45mm NATO/.223 Remington, 30 Round, Yellow, 1 Pack, Polymer, 556BANANA30-30RD
(1)
List: $27.99 $24.99 Save Up to 11%
Best Rated PMC Ammunition 556K X-Tac, 5.56x45mm NATO, 62 grain, Light Armor Piercing, Brass, Centerfire Rifle Ammo, 20, 5.56
PMC Ammunition 556K X-Tac, 5.56x45mm NATO, 62 grain, Light Armor Piercing, Brass, Centerfire Rifle Ammo, 20, 5.56
(103)
List: $14.99 $11.29 Save Up to 25%
Questions & Answers
Will this except an A2 front sight post Expert Answer

Yes, the FN America AR-15 Hammer Forged 18 Inch Barrel will accept a fixed front sight as long as it is compatible with a 0.750" gas journal. You would also need a rifle length gas tube.

by Ethan, Gear Expert, May 2, 2022
Hi, I need to know if this barrel accepts pinned gas blocks or will it only accept a slip on. I know it's .750 diameter, not sure on the rest. Thanks.

You would have to drill the barrel if you wanted a pinned gas block. Normally the block and barrel are drilled together for perfect alignment. You can also just simple the barrel and use a low profile gas block which I would recommend unless you really like having the fixed sight block.

by Jon4324, Verified Owner, March 5, 2021
Customer Reviews
Helpful Positive Review
One of the best barrels on the market by Josh, September 14, 2016
Can't go wrong with this barrel, FN makes barrels for Spikes Tactical and the US Military. Worth the extra money. Only barrels I use. Have read reviews of people shooting 30,000+ rounds with good groups.
2/5 found this helpful
Helpful Positive Review
This barrel is top notch workmanship, as is with most products FNH makes and installation was no problem with the right tools. OpticsPlanet.com was fast with the shipping and made the order process hassle free.
1/1 found this helpful
Read All 2 Reviews
Caliber: .223 Remington , 5.56x45mm NATO Barrel Length: 18 inAdditional Features: Rifle Length Gas System

Code: 57D-ATB-36423

MPN: 36423

UPC: 845737005146

List: $399.00Save 13%
$349.00

Product Info for FN America AR-15 Hammer Forged 18 Inch Barrel Rifle Length Gas System 5.56mm NATO 36423

The FN America AR-15 Hammer Forged 18 Inch Barrel RH Gas System 5.56mm NATO 36423 is the perfect way to improve your rifle by adding an excellent rifling piece. Made from a proprietary Chrome Moly Vanadium (CMV) steel, the FN America AR15 Chamber Rod is hammer forged for greater strength and durability. Next, barrels are air gauged and MP tested to make sure the barrel is free of microstresses and cracks. Finally, barrels are chamfered, deburred, and cryogenically treated to ensure superior performance and accuracy. Using a .750 inch diameter gas block, the FN America AR15 Hammer Forged 18in Barrel w/ RLGS, 1/2 x 28 threading, and has a right hand twist rate. For a great way to make sure you have a top of the line barrel on your weapon, choose the FN America AR15 Hammer Forged 18in Barrel w/ RLGS 5.56mm NATO.image

Specifications for FNH USA AR-15 Hammer Forged 18 Inch Barrel Rifle Length Gas System 5.56mm NATO 36423:

Mfg Item Num:  36423
Type:  BARRELS - RIFLE
Barrel Length:  18
Caliber:  5.56mm NATO
Caliber-Gauge:  .223 REM.
Model Header:  Rifle Length Gas System
Master Model Header:  AR-15 Hammer Forged Barrels

FN America AR-15 Hammer Forged 18 Inch Barrel Rifle Length Gas System 5.56mm NATO 36423 Orderable Models

List of Orderable Models

  • FN America AR-15 Hammer Forged 18 Inch Barrel Rifle Length Gas System 5.56mm NATO , MPN: 36423 , UPC: 845737005146 , Code: 57D-ATB-36423
Compare (0)