10.5" .300 Blackout Complete Upper

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Part Number:105-300BO-COMPLETE

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Add a BCG
Add a Charging Handle

This complete upper includes our new NOMAD Handguard! The NOMAD line of handguards were designed with size and weight in mind, providing the user with multiple picatinny mounting options. The perfect addition to your lightweight build. Our proprietary barrel nut and retention system is a durable and dependable mounting platform, maintaining a slim profile while still providing the strength and stability customers have grown to love from Modern Armory.



  • MA Assembled Upper Receiver
  • 12” NOMAD handguard
  • 10.5" .300 Blackout CMV Barrel
  • Low Profile Gas Block and Pistol Length Gas Tube
  • KVP Linear Compensator
  • Product comes assembled

This complete upper does not include BCG or Charging Handle. These products may be selected as add-ons under the FINISH YOUR BUILD tab

The muzzle brake that comes with this complete upper receiver is NOT pinned nor welded to this barrel.


MA Upper Receiver Features:

  • Precision machined to correct Mil-Specs from 7075 T6 Forged aluminum
  • Machined for use with barrels that use an M4 barrel extension
  • M4 Feedramps
  • Hard- coat anodized per Mil-A-8625F Type III Class II in a matte black finish
  • Ejection port door and forward assist installed
  • .250” takedown pin holes
  • Dry Film Lube on interior bore per Mil-Specs


NOMAD Handguard Features:

  • Front and rear picatinny rail
  • Eliminated center of top rail for weight reduction
  • Quick disconnect sling socket at the 3 and 9 o’clock positions
  • Compatible with low profile gas blocks
  • 1.3” Inside diameter
  • 1.5” Outside diameter
  • Weight is 9.5 oz. without barrel nut
  • Compatible with mil-spec AR15 upper receivers and barrels


10.5" .300 Blackout Barrel Features:

  • Length: 10.5"
  • Twist: 1 in 7
  • Muzzle: 5/8x24 Threaded
  • Material: 4150 Chrome Moly Vanadium
  • Finish: QPQ corrosion resistant finish both inside and out
  • Gas Block: .750
  • Gas Port: 0.80”
  • Gas System Length: Pistol
  • Weight: 19oz
  • M4 Barrel Extension
  • HP and MPI Tested
All of our uppers have had 3 rounds fired through them. They will come with some slight marks on the BCG and charging handle, rest assured all parts are new. We do this for several reasons, 1) to make the upper passes our function test, 2) see number one. The upper will not be cleaned after the 3 round burst.

*Lifetime Guarantee covers manufacturing defects in materials and workmanship, regardless of the age of the product, but it does not cover normal wear and tear. Wear and tear is damage that naturally and inevitably occurs as a result of normal use.

The use of reloaded or remanufactured ammunition will void the warranty, due to the unpredictability of the standards (SAMMI/NATO) adhered to, since reloads of poor quality ammunition may not meet (SAMMI/NATO) specifications, may exceed limits, and therefore may be unsafe.

ITAR: International Traffic in Arms Regulations Controlled
5 Stars
It just arrived so I haven't had a chance to shoot it yet. Such a wonderfully snug fit to my lower receiver and so obviously well-made. This is my first large purchase from Modern Armory and am absolutely going to be a repeat customer based on the quality and workmanship put into this product. A+++++++++++++++++++++++++++
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Reviewed by:  from Kathleen. on 5/7/2020

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