Sons of Liberty Gun Works M4-76 5.56 Barreled AR-15 Upper Receiver - 16"

SKU: M476UPPER-16-556
MPN: M476UPPER-16-556
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The Sons of Liberty Gun Works M4-76 5.56 Barreled AR-15 Upper Receiver is highly enhanced upper for AR-15 enthusiasts seeking a reliable, multi-purpose rifle. This upper receiver features a 16" barrel precision-machined from robust 4150 chrome moly vanadium steel, finished with QPQ Nitride for exceptional durability. The 15-inch M476 free-float M-LOK handguard features additional 45-degree M-LOK attachment points for additional versatility.

This upper receiver includes the forward assist and dust cover pre-assembled but does not come with a BCG or charging handle. To further enhance functionality, a dry film lube is applied to the inside of the receiver, reducing friction with the bolt carrier.


  • Enhanced AR-15 upper
  • 16" barrel with QPQ Nitride finish
  • M476 free float handguard with M-LOK slots
  • Durable 7075-T6 aluminum upper receiver
  • Wedgelock barrel nut for longevity
  • Includes forward assist and dust cover
  • Dry film lube for smooth function

Sons of Liberty Gun Works, a leading custom rifle manufacturer in the United States, specializes in the AR-15 platform, ensuring top-notch craftsmanship and performance. Build your duty-ready rifle with confidence starting this exceptional upper receiver.

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Barrel CoatingSalt Bath Nitride
Barrel Length16
BrandSons of Liberty Gun Works
Caliber Gauge5.56 NATO
FinishHardcoat Anodized
Gas System TypeDirect Impingement
Handguard15 in M-LOK Rail
Muzzle DeviceA2 Flash Hider
Thread Pattern1/2 X 28
California Prop 65 warning

 WARNING: This product can expose you to chemicals, which are known to the State of California to cause Cancer and Reproductive Harm. For more information go to

Ratings & Reviews

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Worth the money

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Without a doubt one of the best uppers I own. I caught it on a sale for a new duty upper and I’m absolutely pleased with it. Great accuracy and reliability.