Complete AR15 Upper Receiver - 5.56 - 4.75" Barrel - 5.5" MLOK

(2 reviews)
Current Stock:
Adding to cart… The item has been added


  • Barrel Length- 4.75”
  • Barrel Material- 41V50 Button Rifled Barrel
  • Chamber 5.56 NATO
  • Twist Rate 1:7
  • Muzzle Device- KAK Flashcan 
  • Extension- M4
  • Gas System- Carbine length
  • Gas Block- Low profile .750 Nitride Finish
  • Upper Receiver- Forged 7075 T6 Aluminum, Precision Machined to M16/M4 Spec
  • Handguard- 5.5”, High Quality 6061 T6 Material Mlok with Proprietary Clamping System and Heavy-Duty Barrel Nut
  • Charging Handle- Milspec with Enhanced Large Billet Latch

BCG (chrome lined phosphate comes standard, K-SPEC Upgrade available)

  • M16 Auto Profile Carrier Machined from Aircraft/ Bearing Quality 8620 Steel, Properly Heat Treated, Ground to Perfection, BlackNitride Finish by H&M
  • Bolt is machined from a single piece aircraft/bearing quality 9310 steel, heat treated properly, precision ground, Shot Peened and MPI’d
  • Firing pin is machined to the mil-spec print from 8740, precision ground, and chrome plated
  • One Piece Billet Fully Machined Enhanced Extractor, Phosphate coated for Increased reliability and corrosion resistance
  • S7 tool steel ejector and extractor retaining pin
  • 4130 Gas Key, precision staked using our hydraulic staking machine
  • KAK Carrier Key Screws- T25 drive, Grade 8, Properly Heat Treated

All KAK complete upper receivers are test fired for feed and function using commercially loaded ammunition



  • 4

    Posted by Brian Hawkey on March 27, 2024

    I only put 4 stars because the coating on the Handguard is pretty bad. It’s rough and not coated entirely in certain spots. I swapped with the Utg Handguard from you guys and that one is awesome. I had a sharps advisable has bcg in the upper at first and I kept getting jams, but omg the KSPEC Bcg runs flawless! I’m going to buy another I love it

  • 5
    556 - 4.75 complete upper

    Posted by Nick Radavich on November 1, 2023

    I purchased this upper a few weeks ago and just got out to shoot it. Using Federal .223 55 gr. target ammo, no failures to feed, fire, or eject in 50 rounds. About a 1" group at 25 yards. H buffer, 3.8 oz. grey top. Ejected perfectly at 3:00. Nice solid hand guard, it's a blast to shoot.