HM Defense MONOBLOC 16 Inch Complete 5.56 AR-15 Upper Receiver with 10 Inch M-LOK Handguard

Click Here for Price
Out of Stock

Join the waitlist to be emailed when this product becomes available


AT3™ Magnified Red Dot Kit - Includes Red Dot & 3x Magnifier


AT3™ 3x Magnified Red Dot Kit – Includes Red Dot, Riser, & 3x Magnifier

3-Pack - Magpul PMAG 30-Round M2 MOE Mag - .223 / 5.56 NATO

3-Pack - Magpul PMAG 30-Round M2 MOE Mag - .223 / 5.56 NATO - MAG571


3-Pack - Magpul PMAG 30-Round M2 MOE Mag - .223 / 5.56 NATO

Magpul 30-Round Bulk AR 15 PMAGS M2 – .223 / 5.56 NATO – MAG571 – Available in 1, 2, 3, 10, 25, 50, and 100-Pack

Cost-Effective Complete Upper Receiver for A High-Performance AR-15 Build

This HM Defense BUP Complete Upper Receiver features a 16-inch 4150 Chromoly barrel with an patented integrally machined gas block, and a carbine gas system. HM Defense has developed a revolutionary gas block that is actually part of the barrel which, greatly improves the barrel harmonics for better accuracy and provides a dependable performance even in severe conditions.

Included in this complete upper is the HM Defense 10 3/8 inch Free Float Picatinny Rail Handguard machined from 6061-T6 aircraft-grade aluminum. Also included is a patented HMB bolt, a charging handle, and a dust cover with an American Flag.

This upper receiver represents a high-quality option that will allow you to complete your next AR-15 for a top-performance build.


  • Barrel: The HM MONOBLOC upper includes an integrally machined patented gas block. Chambered in 5.56 NATO/223 Rem, the 4150 Chromoly barrel is 16 inches in length and features a 1:8 twist ratio and a mid-length gas system. All HM Defense barrels are match grade, tripled honed, and button rifled for superior accuracy.
  • Handguard: The custom HM Defense 10 3/8 inch, free float 1913 Picatinny rail is CNC machined from 6061-T6 aircraft grade aluminum. The rail is compatible with Magpul M-LOK mounting system.
  • Upper Receiver: HM Monobloc upper features a Mil-Spec Forged 7075- T6 M4 Upper Receiver with Type III Class II hard-coat black anodized finish, M4 Feed Ramps, and a 1913 Picatinny rail flattop.
  • Components: HM Defense Monobloc upper includes an M16 bolt carrier group with patented HMB bolt and Mil-Spec components and charging handle. Includes dust cover engraved with an American flag.
  • Muzzle Brake: HM Defense Monobloc upper includes CNC machined muzzle brake.
  • Barrel Finish: Rifle Black Cerakote finish.


  • Type: Complete Upper Assembly
  • Barrel Length: 16″
  • Caliber: .223/5.56 NATO
  • Color: Black
  • Handguard: 10 3/8″ M-LOK Rail
  • Finish: Anodized
  • Fit: AR15
  • Barrel Twist Rate: 1:8

Have Questions About this Product?