Aero Precision M4E1 Threaded Barreled Upper Receiver .300 BLK Pistol Length – ATLAS S-ONE – 10″


  • M4E1 threaded upper receiver
  • Forged 7075-T6 aluminum
  • Assembled forward assist and dust cover
  • 9” ATLAS S-ONE M-LOK handguard
  • Hardcoat anodized
  • 10” .300 Blackout barrel
  • Machined from Chrome Moly Vanadium
  • Pistol length gas system
  • 1:7 twist rate
  • Threaded 5/8×24
  • A2 flash hider
  • Salt Bath Nitride finished
  • Does not include BCG or charging handle


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SKUAPAR700302M4 Category

Note: This barreled upper receiver assembly has a barrel length under 16” and is therefore subject to all NFA rules and regulations. Know your local laws before purchasing.

If you’re looking to build a high quality .300 BLK AR pistol, look no further than the Aero Precision M4E1 Threaded Barreled Upper Receiver! This complete upper receiver assembly comes with a 10″ .300 Blackout barrel and a pistol length gas system, making it perfect for your next build. The forged 7075-T6 aluminum construction ensures durability, while the billet design provides a unique, stylish look. The ATLAS S-ONE free float handguard provides ample space for accessories and features M-LOK slots for easy installation. Plus, this barreled upper receiver assembly includes the forward assist and dust cover.


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