AR-15 16" M16 U-Build BarDef Complete Upper/Lower AR15 Kit 556
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BarDef U-Build Complete AR15 556 M4 Carbine Kit is being offered a low-low price! Lower Receiver not included and can be purchased through an FFL dealer. This Barrier Defense carbine length upper features a Mil-Spec M-16 bolt carrier group, phosphate finish, M4 profile barrel. The A3 upper will attach to any standard AR-15 lower receiver and comes complete with charging handle, forward assist, ejection port cover, bolt and bolt carrier assembly. With a 1 in 8" twist, the 16" barrel provides incredible accuracy with a full range of bullets. It's tipped with an A2 flash hider. This upper is a great platform for a red dot or flip-up sights (sold separately). This product comes with the Barrier Defense lifetime warranty.

This kit also includes a Mil-Spec 6-position stock assembly. The buffer tube is machined from 6061-T6 aluminum. It includes Mil-Spec buffer, and spring. The super durrable stock is comfortable and cool looking and tough to withstand years of use and abuse. The kit comes ready for you to assemble so you can brag that U-Built-It.

This Parts kit includes everything needed to build a complete upper and lower, except a stripped lower receiver. All parts are made to standard military specifications.

****Know your states laws when purchasing this item.


  • (1) 16" Barrel 1:8 Twist/Carbine Gas System/Parkerized/Non-chrome lined (more accurate)
  • (1) BCG- 5.56 NATO Bolt Carrier Group 
  • (1) Slim Mlok Free Float Hand Guard15"
  • (1) Lower Parts Kit w/Trigger & Hammer
  • (1) Mil Spec 6-Position Stock
  • (1) 750 Gas Block
  • (1) Carbine Length Gas Tube
  • (1) Standard Receiver End Plate
  • (1) Mil-Spec/Commercial Castle Nut/Steel
  • (1) Mil-Spec Buffer Tube/Alum.
  • (1) 3 oz. Buffer
  • (1) Buffer Tube Spring
  • (1) Mil-Spec Charging Handle Alum.
  • (1) Dust Cover
  • (1) Forward Assist
  • (1) 1/2"x28 Thread Bird Cage A2 Muzzle Brake
  • (1) Pistol Grip/Black 
  • (1) Upper Receiver 5.56/.233/.300AAC, M4 Feed Ramps



Lower Parts Kit Includes

  • Bolt Catch
  • Bolt Catch Plunger
  • Bolt Catch Roll Pin
  • Bolt Catch Spring
  • Buffer Retainer
  • Buffer Retainer Spring
  • Disconnector
  • Disconnector Spring
  • Hammer
  • Hammer Pin
  • Hammer Spring
  • Magazine Catch
  • Magazine Catch Button
  • Magazine Catch Spring
  • A2 Pistol Grip
  • Pistol Grip Lock Washer
  • Pistol Grip Screw
  • Pivot Pin
  • Pivot Pin Detent
  • Pivot Pin Detent Spring
  • Safety Selector
  • Safety Selector Detent
  • Safety Selector Detent Spring
  • Takedown Pin
  • Takedown Pin Detent
  • Takedown Pin Detent Spring
  • Trigger
  • Trigger Guard
  • Trigger Guard Roll Pin
  • Trigger Pin
  • Trigger Spring


  • Item #: 5MM15-Kit

AR-15 16" M16 U-Build BarDef Complete Upper/Lower AR15 Kit 556

Price: $679.00
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Availability: In-Stock
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