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HM Defense

HM Defense DefenderM5 Monobloc Rifle - HMB Bolt - Monobloc Barrel 5.56 NATO / 223 Rem

Product Code : DefenderM5


Mfg Item #: DefenderM5

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DefenderM5 Monobloc Rifle - HMB Bolt - Monobloc Barrel 5.56 NATO / 223 Rem


PLEASE READ! Current lead time is 30 days. 30 days from the time payment posts in our system.



The DefenderM5 features HM patented MONOBLOC HBAR barrel with an integrally machined gas block. Chambered in 5.56 NATO/223 Rem, the 4150 Chromoly barrel is 16 inches in length, 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.



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.


Lower receiver:

The DefenderM5 features a Mil-Spec Forged 7075-16 Lower Receiver with Type Ill Class Il hard-coat black anodized finish.


Upper Receiver:

DefenderM5 features a Mil-Spec Forged 7075-16 M4 Upper Receiver with Type Ill Class II hard-coat black anodized finish, M4 Feed Ramps, and a 1913 Picatinny rail flat top.



HM Defense rifles include a M16 bolt carrier group with patented HMB bolt and Mil-Spec components, including the trigger & fire control group, charging handle and buffer tube/spring. Custom Trigger Guard, Monobloc Dust Cover, CNC Machined Muzzle Brake


End Plate:

HM Defense rifles feature a custom Quick Disconnect (QD) end plate.



Rifle features a black Mil-Spec HM stock and enhanced grip.



A magazine is included with each rifle.



  • Gas block integrally machined as part of barrel
  • Eliminates gas block installation and alignment
  • Improved barrel harmonics for better accuracy
  • Dependable performance in severe conditions

  • Barrel: Available on DefenderM5, DefenderM5L, RaiderM5 (5.56 NATO/223 Rem) and AR-10 (308 WIN.) models, with a mid-length and rifle gas systems. All HM Defense barrels are match grade, tripled honed and button rifled for superior accuracy. Barrels are manufactured in 4150 Chromoly.
  • Barrel Extension: All HM barrels feature Mil-Spec M4 feed ramps, properly installed and head spaced with gauges.
  • Gas Block: The HM MONOBLOC gas block is machined from the solid barrel blank and is an integral part of the barrel.
  • Barrel Length: HM MONOBLOC barrels are produced in 12.5 and 16 inch length with a threaded muzzle.

    HMB Battle Ready HM Bolt

    Existing Mil-Spec M16, & AR-15 bolts have a natural weak point where the cam pin hole passes through the bolt. Under extensive use, including the stress of combat, the bolt can fail at this critical location.

    The HMB™ bolt by HM Defense eliminates the pass through cam pin hole and replaces it with a cam pin socket and tapered cam pin design. This new patented design eliminates the natural weak point of Mil-Spec bolts by significantly increasing the amount of metal (and strength) at the cam pin location. The result - No more broken bolts! HMB" bolt cross section

    Additional benefits of the HMB design include the elimination of the cam pin hole staking, reduction in potential cam & firing pin contact and a smoother operation of the Bolt Carrier Group (BCG).

    Best of all, the HMB™ is 100% compatible with Mil-Spec M16, & AR-15 BCGs and can be installed as a drop-in bolt replacement in any existing M16 or AR-15 rifle. Available on GuardianF5, DefenderM5, DefenderM5L and RaiderM5 Models.

Determined at checkout.