Cheers Beers Happy Tavern

AR-15 Build Guide

Detailed Information for Building an AR-15

AR-15 Assembly

AR-15 - Detailed Step By Step Assembly / Build Instructions (HD)

The AR-15 is the most common rifle in the U.S.A. It is a semi-automatic rifle modeled after the military's automatic M16. The rifle is modular and can be customized with many different accessories. In this video, I discuss the full assembly of an AR-15 from individual parts.

Part 1: Lower Receiver Assembly

Part 2: Upper Receiver Assembly

Part 3: Live Fire Testing [01:01:57]

Tools Required:

  1. Vise
  2. AR-15 Lower Receiver Vise Block
  3. Small Hammer
  4. Set of Roll Pin Punches
  5. Screwdriver
  6. AR-15 Barrel Wrench
  7. Set of Allen Wrenches (i.e., Hex Wrenches)
  8. Gun Oil
  9. Pivot Pin Installation Tool
  10. Torque Wrench
  11. Razor Blade
  12. AR-15 Upper Receiver Vise Block
  13. Snap Ring Pliers
  14. 5.56 NATO / .223 Headspace Gauge
  15. Clamp or Vise with rubber guards

Optional Tools (not required, but they make the job easier):

  1. Drill (if you desire to dimple barrel)
  2. Blue Loctite
  3. Dummy Cartridge
  4. Brush and Rag for Cleaning
  5. Needle Nose Pliers
  6. Empty 5.56/.223 Shell Casing
  7. Torque Screwdriver
  8. Air Compressor
  9. Pencil
  10. Center Punch (if you desire to dimple castle nut)
  11. Tape
  12. Wood Block
  13. Rubber Mallet


Parts Required:

  1. Stripped Lower Receiver
    1. Purchase from Gun Store or FFL
    2. Depending on state laws, purchase from a private seller.
    3. Make your own. (Using a drill press, 3D printer, milling machine, etc.)
  2. Lower Parts Kit (LPK)
    1. Includes: Magazine Catch Button, Magazine Catch, Magazine Catch Spring, Bolt Catch, Bolt Catch Plunger, Bolt Catch Roll Pin, Bolt Catch Spring, Pivot Pin, Detent x 2, Detent Spring x 2, Takedown Pin, Safety Selector, Selector Detent, Selector Spring, Trigger Guard, Roll Pin, Buffer Catch, Buffer Catch Spring
    2. Some LPKs do not include a trigger group
      1. Trigger, Trigger Spring, Hammer, Hammer Spring, Disconnector, Disconnector Spring, Hammer and Trigger Pins
    3. Some LPKs do not include a pistol grip
      1. Pistol Grip, Grip Screw
  3. Trigger/Hammer Group (if not included in LPK)
  4. Pistol Grip (if not included in LPK)
  5. Buffer Tube Kit
    1. Buffer Tube
      1. If making an AR-15 Pistol, use a pistol tube instead.
    2. Nut
    3. Buffer Spring
    4. Receiver end plate
    5. Castle Nut
    6. Buffer
      1. Various Weights: H1, H2, or H3
  6. Buttstock
    1. Illegal on an AR-15 Pistol (must use pistol tube)
  7. Barrel and Barrel Nut
  8. Handguard
    1. Sometimes includes a special barrel nut.
  9. Gas Block Kit
    1. Gas Tube
    2. Gas Block
    3. Gas Tube Pin
  10. Flash Hider/Muzzle Brake and Crush Washer
  11. Stripped Upper Receiver
  12. Ejection Port Cover Kit
    1. Ejection Port Cover
    2. Hinge Pin
    3. Hinge Pin Snap
    4. Hinge Spring
  13. Forward Assist Kit
    1. Forward Assist (with pre-installed Pawl)
    2. Forward Assist Retainer Pin
    3. Forward Assist Spring
  14. Bolt Carrier Group
    1. Bolt
      1. Extractor Pin, Extractor with Spring, and Bolt
    2. Carrier
      1. Carrier, Cam Pin, and Retaining Pin
    3. Firing pin
  15. Charging Handle
    1. with spring, latch, and roll pin if purchased separately.
  16. Magazines
    1. Variety of sizes: 10, 20, 30, etc...
  17. Sights/Optics