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L4 Duty Upper Receiver Group
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L4 Duty Upper Receiver Group


Muzzle Device


Gas Tube

Gas System


Upper Receiver

Bolt Carrier Group

Charging Handle


The L4 Duty Upper Receiver Group is a Mil-Spec AR-15 upper receiver group that you can fully customize to your liking.

Includes manuals.

Made in the USA! Comes with a lifetime warranty.

Upper Receiver

  • Mil-Spec Forged
  • CNC Machined of 7075-T6 Aluminum
  • Black Type III Hard Coat Anodized
  • M4 Feed Ramps
  • T-Marks
  • Forward Assist

Muzzle Device

  • Classic A2 Style
  • 1/2x28" TPI
  • 5.56/.223 Caliber


  • Barrel Material: 4150 CMV Steel
  • Barrel Type: Button Rifled
  • Barrel Caliber: 5.56 NATO
  • Barrel Twist: 1:8
  • Barrel Length: 10.5"
  • Barrel Profile: Gov't/Socom
  • Barrel Gas System: Carbine
  • Inside Finish: Black Nitride
  • Outside Finish: Black Nitride
  • Muzzle Thread: 1/2-28 TPI (Threads Per Inch)
  • Gas Block Diameter: .750"
  • Gas Block Journal Length: 1.9"
  • Barrel Extension: M4
  • Weight: 1.10 lbs
  • Magnetic Particle Inspected!
  • 11-degree Target Crown

Gas System

  • Direct Impingement
  • Geissele Super Gas Block
  • Low Profile Gas Block CNC Machined of 4140 hardened steel
  • Pistol Length


  • Geissele Super Modular Rail MK13 M-LOK
  • CNC Machined of 7075-T6 Aluminum
  • Type III Hard Coat Anodized
  • 1.27" Inner Dimension
  • 2.044" Outer Dimension at Picatinny
  • 1.52" Outer Dimension in M-LOK Sections
  • 7" Length
  • M-LOK

Bolt Carrier Group

  • M16 Full Auto Profile
  • Properly Staked Gas Key
  • Salt Black Nitride
  • With Forward Assist Serrations
  • Laser Engraved with Lionadi Lion Logo
  • Shot Peened to Mil-Spec
  • Magnetic Particle Inspected (MPI)
  • Bolt Material: 158 C | 9310 Steel
  • Gas Key Material: 4130 Steel; Grade 8 Gas Key Screws
  • Extractor Material: 4140 Steel
  • O-Ring: Mil-Spec (3)
  • Cam Pin Material: 8620 Steel
  • Firing Pin Material: 416 Stainless Steel

Charging Handle

  • Radian Weapons Raptor-LT
  • CNC Machined of 7075-T6 Aluminum
  • Type III Hard Coat Anodized
  • Over-Molded with High-Strength Fiberglass Reinforced Polymer

Our Build Process

All barrels are dimpled during the assembly process if they are not already dimpled. Gas blocks set screws are torqued to the spec of the specific gas block, then Rocksett is applied. Gas blocks are not pinned. Muzzle devices have Rocksett applied to ensure they do not spin off after heavy use. Handguard screws are torqued to spec and have blue Loctite applied. We use Umbrella Corporation Gun Grease on the barrel nut threads. All barrel nuts are backed off twice before being torqued down to spec on the third time. All products are left for 24 hours before being test fired after being assembled to ensure all loctite/rocksett has cured. If you have any specific questions or concerns about our build process, please contact us.

All products are test fired twice in shop to ensure proper function. Fired shells are included.

Standard Options

  • Muzzle Device: A2 Flash Hider
  • Barrel: Faxon 10.5" Gov't / Socom, 5.56x45 NATO, Carbine-Length, .750 dia
  • Gas Tube: Stainless Steel Gas Tube
  • Gas System: Standard Rail or Barrel Gas Block
  • Rail: Geissele MK14 9.5" M-LOK Rail (Black)
  • Upper Receiver: Lionadi A4 Upper Receiver, Forged (Black)
  • Bolt Carrier Group: Lionadi Bolt Carrier Group (Black Nitride)
  • Charging Handle: Radian Weapons Raptor-LT Charging Handle (Black)

Shipping Times

All firearms are built to order. Please allow up to 8-12 weeks for completion after FFL requirements are completed.

If a delay occurs due to missing, or back-ordered, parts from a vendor we will notify you by email.

To ensure the fastest processing of your order ensure you have already verified with your FFL the ability to take possession of the firearm for the transfer.

During peak demand periods of the year orders may take an additional 1 - 2 months to process. We will notify you by email if your order is affected.

All orders are charged at the time of placing. This will keep your place in line. If you want to confirm order fulfillment time before purchasing please don't hesitate to contact us.

Your firearm may differ from the images shown.

State Restrictions

Lionadi firearms can be shipped unmodified to all states excluding California, New York, Massachusetts, New Jersey, and Connecticut. Our non-NFA and non-pistol firearms have a California compliant option where we install a Mag Lock as well as include a limited capacity magazine. We do not manufacture an AWB state (NY, NJ, CT, and MA) compliant firearm at this time. We also will not ship an upper receiver (stripped or complete) to an AWB state as they do not have permanently pinned muzzle devices and by default have removable flash hiders.

While we do not offer an AWB compliant firearm or upper direct, you may choose to have your purchase shipped to an FFL not in an AWB state to make the modifications for AWB compliance. We don't provide this service but do have options that can make this process easier for you. If you choose this option it is highly recommended to choose the PSR stock, and SureFire Socom muzzle brake that can be permanently pinned by the intermediary FFL. If we receive a lot of requests for AWB compliant options we may begin offering AWB compliant options in the future.

You are responsible to follow local and state laws. Check https://www.nraila.org/gun-laws/state-gun-laws/ for laws in your state.

Mixed Ammunition

For some firearms we offer the same model in various calibers. ALWAYS ensure you are using the proper ammunition for your firearm. Failure to do so can result is injury, massive damage to the firearm, and perhaps even death.

California's Proposition 65

This product can expose you to chemicals including lead, which are known to the State of California to cause cancer and birth defects or other reproductive harm. For more information, go to - www.P65Warnings.ca.gov

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