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How to Install a Lower Parts Kit: Part 1

5.56 Freedom AR15 Build Kit (16" Barrel & M-Lok Handguard) with Fire/Safe 80% Lower

You’ve come to the most dreaded part of the 80% lower project: Installing the guts of the fire control group, magazine assembly, and safety. Fear not! Below is a detailed, step-by-step instructional guide: How to Install a Lower Parts Kit! We’ll assume you already have your Lower Parts Kit and that you understand the individual parts labelled in the kit.

Tools for Installing a Lower Parts Kit

The following tools are highly recommended for this install:

  •         AR-15 Roll Pin Punch Set
  •         Long-Arm Hex Key Set
  •         Brass Gunsmithing Hammer
  •         Small rubber mallet
  •         AR-15 Armorer’s Wrench
  •         Magazine Vise Block
  •         AR-15 Build Mat

Step 1: The Magazine Catch Assembly

  1.       Insert the magazine catch into the long hole on the left side of the receiver.
  2.       Place the magazine release spring into the magazine release hole on the other side.
  3.       Screw the magazine release button onto the threaded end of the magazine catch.
  4.       Use a punch to press the button enough to turn the catch clockwise to tighten.
  5.       Continue tightening until the threaded end is flush with the button.

Step 2: The Trigger Guard Assembly

  1.       Locate the trigger guard and two trigger guard roll pins.
  2.       Press the roll pin into the appropriately sized hole at end of the trigger guard.
  3.       Slide the roll pin and trigger guard into the gap behind the magazine well.
  4.       Use light pressure or a small rubber mallet as necessary to seat the guard.
  5.       Swing in and line up the trigger guard’s other hole with the hole in front of the grip.
  6.       Lightly tap the appropriate roll pin into the trigger guard and receiver.

Step 3: The Bolt Catch Assembly

  1.       Locate the bolt catch, bolt catch buffer, bolt catch roll pin, and bolt catch spring.
  2.       Place the spring on the buffer drop the assembly into the hole above the magazine latch.
  3.       Place the bolt catch into the bolt catch area.
  4.       Line up the roll pin hole while pressing the bolt catch onto the plunger and spring.
  5.       Press the bolt catch roll pin into place. Use a punch and brass hammer as necessary.

Step 4: The Trigger Assembly

  1.       Locate the trigger, hammer, trigger spring, hammer spring, and disconnector spring.
  2.       Attach both springs to the appropriate assembly.
  3.       The ends of the hammer spring should be oriented down and in front of the hammer face.
  4.       The ends of the trigger spring should be oriented down and in front of the trigger.
  5.       Rest the large end of disconnector spring atop the trigger in the disconnector spring pocket.
  6.       Place the disconnector into the trigger. The square pocket of the disconnector should rest atop the disconnector spring.
  7.       Place the assembly into the lower receiver, allowing the trigger to pass through the oval bottom.
  8.       Press down on the disconnector to line up the fire control group’s holes.
  9.       Insert the trigger pin through the receiver and fire control group. Use a punch and brass hammer as necessary to seat it.
  10.       Ensure both springs of the fire control group rest atop the trigger pin.
  11.       Apply pressure to the hammer to line up the second trigger pin hole set.
  12.   Insert the second trigger pin through the receiver and fire control group. Use a punch and brass hammer as necessary to seat it.

We’re almost finished! Take a break and come back for Part 2 of How to Install a Lower Parts Kit!


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