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AR-15 13.9" Intermediate 5.56 Upper - Made to Order

Bexar Arms

Our Price: $1,125.00
(2 reviews) Write a Review
Made to Order, typically ships within 2 weeks.
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  • Radian Raptor-LT AR-15/M16 Charging Handle
  • Radian Raptor-LT AR-15/M16 Charging Handle
  • Radian AR-15/M16 Raptor Ambidextrous Charging Handle
  • Radian AR-15/M16 Raptor Ambidextrous Charging Handle
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It's dangerous to go alone! Take this.
Select your choice of parts from the available options and we'll assemble an upper just for you. Because these uppers are made to order, please allow for up to two weeks before your upper ships.

Uppers purchased with muzzle devices will be permanently attached to meet or exceed 16" overall barrel length.

Uppers purchased with no muzzle device are subject to all NFA Rules and Regulations, as well as all Federal, State, and Local Rules and Regulations.


We chose to design our own 13.9" barrel utilizing the Noveske style Intermediate gas system length in order to create a barrel with the shortest possible dwell time while maintaining unsuppressed reliability. The short dwell time of this 13.9" Intermediate barrel has some very distinct benefits over running a midlength gas system and can be run suppressed or unsuppressed reliably. Particularly when shooting suppressed, the short dwell time helps reduce the amount of gas blowback making for a more pleasant suppressed shooting experience.

All barrels will be dimpled and have their feed ramps polished. Feed ramps will also be contoured to match the upper receiver if necessary.

  • 13.9" 5.56 NATO
  • 4150 CMV Steel Construction
  • Noveske Style Intermediate Gas System
  • 5R Button Rifled
  • 1:7 Twist
  • Tapered Barrel Profile
  • Muzzle Thread: 1/2-28
    • Square Muzzle Shoulder
  • .625 Gas Block Journal
    • 1" Journal Length
  • 0.0995" Gas Port
  • Barrel Extension: M4 Feed Ramps
    • Hand Polished
  • 11 Degree Target Crown
  • Magnetic Particle Inspected
  • Black Nitride Finish
  • 1lb 5.9oz (1.37 lbs)


Our very own eXcise Optimized Handguard is packed with practical features while keeping overall weight reasonable. Perhaps most notable, yet oftentimes overlooked by other companies, is the nitrided steel reinforced QD sling sockets.

  • 12.9" eXcise Optimized Handguard
  • MIL-A-8625 Type III Class II Black Hard Coat Anodized
  • Slim Profile with 1.3" ID and 1.5" OD
  • 7075-T6 Barrel Nut
  • 6061-T6 Aluminum Body
  • 4140 Black Nitride Retention Plate
  • Nitrided Steel QD Sling Mount Inserts (2x)
    • Retained from both the front and the back
  • Steel Clamp Screws thread into Steel Retention Plate
    • No Helicoils or Aluminum Threads to strip
  • Anti-Slip Retention Plate keys into Barrel Nut
  • Anti-Rotation Tabs
  • 9.6oz Total Weight Including Barrel Nut and Mounting Hardware

Upper Receiver

Your choice of black anodized Aero Precision upper receivers. Options include the standard Mil-Spec style upper, No Forward Assist "Slick Side" upper, M4E1 Threaded upper, and M4E1 No Forward Assist upper. You also have the choice to have the upper receiver squared or not.

Gas Tube

Noveske Style Intermediate gas tube in 304 stainless steel.

Gas Block

Your choice between a standard low profile gas block and the Superlative Arms adjustable gas block. If shooting suppressed, we recommend the Superlative Arms AGB.

  • If shooting unsuppressed only, the standard low profile gas block is the perfect option.
  • If shooting suppressed only, the Superlative Arms AGB can be tuned to your suppressor and then left alone for a more optimized shooting experience.
  • If shooting both suppressed and unsuppressed, the Superlative Arms AGB can be adjusted between your suppressed and unsuppressed shooting to maximize both shooting conditions.
  • Our URG will function in both the suppressed and unsuppressed conditions with the standard low profile gas block should you not want the added cost or complexity of the Superlative Arms AGB.
    • Using recoil heavier springs and/or buffer weights can be used to help tune your URG in lieu of an AGB.

  • If shooting steel cased/underpowered ammo unsuppressed, consider using a lighter buffer such as a Carbine or H1.
  • If shooting suppressed with any ammo, consider using an H2 or heavier buffer.

Muzzle Device

Your choice of the Dead Air Keymo Flash Hider or Muzzle Brake, Surefire Flash Hider or Muzzle Brake, or no muzzle device. The Dead Air and Surefire muzzle devices are suppressor mounts for their respective attachment systems. Dead Air and Surefire muzzle devices will be permanently attached to reach an overall barrel length that meets or exceeds 16"

For dedicated suppressed use, we personally recommend using any of the muzzle brake options to help protect the blast baffle in your suppressor.

Uppers purchased with no muzzle device are subject to all NFA Rules and Regulations, as well as all Federal, State, and Local Rules and Regulations.

Bolt Carrier Group

Your choice of BCG with 9310 or C158 bolt. All BCG's are checked for headspace with your upper.

  • Individually Gauged and Inspected In House
  • Machined and Toleranced Specifically to be Nitrided
  • Your choice of 9310 or C158 Bolt
    • Black Nitrided
    • Shot Peened, Properly Heat Treated, and MPI Inspected
    • Inconel X750 Extractor Spring
    • Inconel X750 Ejector Spring
  • Billet Extractor
    • Billet 4140 Steel
    • Phosphated
    • Extractor Viton O-Ring included
  • 8620 Carrier
    • Back Nitrided
    • Full Auto M16 Profile
  • 4140 Billet Gas Key
    • Black Nitrided
    • Sealed to Carrier with Permatex 27010 "Red Gel"
    • "Decked" before Installation
    • Dimple Staked In House with OCKS Screws
  • 4140 Billet Cam Pin
    • Black Nitrided
  • Enhanced Helical Gas Rings
    • Guaranteed to pass the "Gas Ring Test" with our Carriers
  • Mil-Spec Firing Pin
    • Swiss Turned from 8640 Steel
    • Hard Chrome Plated

Charging Handle

Option to include a Radian Raptor or Aero Breach ambidextrous charging handle.

Iron Sights

Option to include sights with your upper.

Here at Bexar Arms, we take our work seriously. Our Upper Receiver Groups (URG's) carry a Limited Lifetime Warranty covering materials and workmanship. This warranty does not cover extreme abuse or misuse, but it does cover anything that might happen to your upper under any reasonable circumstance. We will replace your barrel for free if you shoot it out. We will replace your entire URG for free should you lose it in a house fire, vehicle fire, or through other disastrous circumstances outside of your control. We will not replace your URG if you damage it by purposefully using it in a manner that it was not intended for.

2 Reviews Hide Reviews Show Reviews

  • 5
    Well built upper, incredible suppressor host

    Posted by Dylan on Dec 21st 2023

    I recently hit ~1500 round mark through this upper and I'm exceptionally pleased with it. With the SupArms AGB, Surefire 556 Mini2, and JP SCS-H2, it is the smoothest shooting semiauto I own, by far. The attention to detail paid to ensuring a leak-free gas system is remarkable, this is not just a bunch of AR parts LEGO'd together. I would absolutely recommend to anyone looking for a dedicated-suppressed upper receiver group, the build quality and short dwell time make tuning the weapon system a dream.

  • 5
    13.9 URG

    Posted by Phillip V on Dec 28th 2022

    I am really impressed with the build quality of Bexar Arms. the URG is Accurate and can consistently hit 300 yards consecutively on a 55 grain. Phil makes sure each upper is properly made and inspected to the highest quality possible. If you are looking for a great upper, This is it.