Aero Precision M4E1 Threaded Barreled AR-15 Upper Receiver 5.56 Mid-Length – ATLAS S-ONE – 14.5″


  • M4E1 threaded upper receiver
  • Forged 7075-T6 aluminum
  • Assembled forward assist and dust cover
  • 12” ATLAS S-ONE M-LOK handguard
  • Hardcoat anodized
  • 14.5” 5.56 NATO barrel
  • Machined from Chrome Moly Vanadium
  • Mid-length gas system
  • 1:7 twist rate
  • Threaded 1/2×28
  • A2 flash hider
  • Salt Bath Nitride finished
  • Does not include BCG or charging handle


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SKUAPAR700304M5 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.

This upper receiver group comes with everything you need to get started, including a 14.5″ 5.56 barrel and the ATLAS S-ONE M-LOK handguard. The forged 7075-T6 aluminum upper receiver is both strong and good looking, with a billet machined look that will match your lower receiver and handguard perfectly. The ATLAS S-ONE free float handguard is 12″ long and features a 1.3″ inner diameter that surrounds the low profile gas block and mid-length gas tube. This barreled upper receiver group does not include a BCG or charging handle, so you can choose your favorites for your build.


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