AR15 Mark 1 Builder Set




All rifles and lower receivers must be shipped to a FFL

Lower Receiver:

Blackout Defense Mark 1 lower receivers are the ONLY receivers on the market that will stop the rattle, wobble, and slop in your rifle platform.  Our patented design incorporates aerospace-grade composite into a precision-machined groove to create a rigid assembly that is still easy to field strip.  In addition, our receivers are precision machined from billet 7075-T6 aerospace grade aluminum, which offers superior strength and rigidity over the more commonly used 6061 aluminum.  The receivers are then sandblasted by hand with aluminum oxide and hard coat anodized for a tough, matte finish.

  • CNC-machined from 7075-T6 American made billet aluminum
  • Reinforced in critical areas such as the buffer tube and the trigger pin joins
  • Patented PRESSLOCK Anti-Rattle design to eliminate Rattle/Wobble/Slop
  • Proprietary aerospace grade compression pad (yellow strip) for a rigid assembly yet Easy field strip (5 strips included with each purchase)
  • Life time FREE supply of yellow compression pad
  • Wire EDM cut magazine well
  • Flared magazine well for easy magazine changes
  • Mil-Spec component compatible
  • Over-sized trigger guard
  • Threaded bolt catch roll pin – allows for simple installation of the bolt catch and virtually eliminates the chance to damage the finish during installation (roll pin is included)
  • Threaded trigger slack adjuster – allows users to lock-in the mil-spec trigger pins using a nylon tipped tensioning set screw inserted through the grip tang of the lower receiver. This prevents the trigger pins from waking out (green tip set screw is included)
  • Threaded trigger slack adjuster should not be used with Blackout Defense drop in triggers
  • 0.154″ diameter trigger pin holes
  • Threaded Takedown Pin Detent Recess – Allows users to easily install the takedown Pin detent and spring with the use of a 4-40 set screw (steel tip set screw is included)
  • Hex Key 1/16″ (for 6-32 bolt catch roll pin) 5/64″ (for 8-32 trigger slack adjuster) and 0.05″ (for 4-40 takedown pin detent recess) are included.
  • Deep engraved safety selector
  • Type III Class 2 hard anodized
  • 100% made in the USA

Upper Receiver:

  • CNC-machined from American made billet aluminum
  • 5 Axis machined in one setup for ultimate precision
  • Precision Carrier bore internal diameter to aid long range accuracy performance
  • Increased wall thickness for added rigidity
  • Engraved “T” numbers
  • 1913 picatinny Rail flat top
  • Mil Spec Type III class II hard coat anodized Black
  • Compatible with Mil spec parts
  • Compatible with most aftermarket handguard/rail systems
  • Lifetime warranty against manufacture defects
  • Available with and without forward assist
  • Machined Shell deflector & dust cover opening
  • M4 feed ramps


  • 6000 series extruded Aluminum Mil Spec Type 3 Class 2 Hard Black anodized
  • Aluminum 7075 type 3 class 2 hard anodized barrel nut
  • 17-4PH cored stainless steel rail mounting attachment
  • Anti-rotate tabs time rail to upper receiver
  • 4140PH alloy steel nitride finished QD sling sockets inserts one on each side
  • No Barrel nut shims required for installation
  • Does not contact or apply side loads to gas tube
  • Inner Diameter of handguard – 1.315″
  • Machine engraved “T” markings
  • Includes barrel nut wrench
  • Barrel Nut diameter- 1.378″
  • Compatible with most known low-profile gas blocks
  • Overall rail dimensions are 1.96″ wide x 2.195″ height
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