The Ultimate Guide To Build An AR-15(Build AR-15 Parts)

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AR-15 Parts and How to Build Guide

The AR-15 is a common rifle in the American civilian gun market. It’s a semi-automatic version of the military M16 rifle. AR-15scome in different styles depending on the manufacturers. It’s because it’s a highly customizable gun. Also, depending on the features it holds, it can either comes as a pistol or a rifle.

The AR-15 is an all-around firearm that most Americans use for hunting, self-defense purposes, and shooting competitions. Additionally, most people interested in training in shooting rifles tend to use the AR-15s. Different lawmakers hold varying opinions about the AR-15s.

Building an AR-15 is a fascinating process when you have the right parts and tools. The below guide highlights the essential parts, tools, and steps to follow while building an AR-15 rifle.

Parts Needed to Build an AR-15

A standard AR-15 should compromise of the following parts: However, you can decide to add other accessories such as scopes, laser lights, etc.

Important Tools for Building an AR-15

  1. Bench Vise
  2. Roll pin punch set
  3. Roll pin holder
  4. Armorer’s wrench
  5. Torque wrench
  6. Brass hammer
  7. Pliers
  8. Allen Wrench set

Bit by Bit on How to Build an AR-15

The AR-15 is mainly divided into three parts, i.e., the Lower Receiver Parts, Upper Receiver Parts, Grips, and Muzzle devices. This guide discusses how to assemble all of the parts mentioned above to make a functional AR-15.

Assembling an AR-15 Upper Receiver Assembly

  1. The first thing should be setting up your Upper Receiver in a Vise Block.
  2. Start by installing the Ejection Port Cover on your Upper Receiver. Align the Ejection Port Cover and the Spring well on the side of the Upper Receiver.
  3. You should also twist the Spring while fitting it in the cover channels to create tension.
  4. Insert your pre-assembled Forward Assist into its respective slot.
  5. Slide the Spring over the Forward Assist and ensure the front tip of the Forward Assist moves and curves in one direction.
  6. While fitting in the Forward Assist, the movable part should face the Upper Receiver’s outer direction. Then use a Brass Hammer and Roll Pin Punch to drive in the Roll Pin on the Forward Assist’s hole.
  7. The next stage will entail installing the Barrel on the Upper Receiver.
  8. Apply some grease on the Barrel’s rear end as well on the inner part of the Upper Receiver where the Barrel will be attached. It makes it easier fitting our Barrel.
  9. Ensure the little knob on the Barrel aligns with the small hole on the Upper Receiver.
  10. Proceed and install your Barrel Nut. Also, ensure your Gas Tube holder is not blocked. Use your Torque Wrench to tighten the nut. Torque up until it’s well-aligned.
  11. Insert the Gas Tube into the Gas Block.
  12. Confirm that the hole at the end of the Gas Tube front is aligned with the hole on the Gas Block. Then insert a Roll Pin to keep the gas tube in position.
  13. Position your Gas Tube and Gas Block on the Barrel as the Gas Block’s rear side gets into the Upper Receiver’s Gas Tube holder.
  14. Then tighten your Gas Block to maintain the aligned position.
  15. Fit in your Handguard/ Rail over the Barrel and join to the Upper Receiver.
  16. Take time to adjust your Handguard and position to a perfect level.
  17. Now, it’s time to install your Bolt Carrier Group (BCG) and Charging Handle into the Upper Receiver. Both go to the rear part of the Upper Receiver.
  18. Drive-in your Charging Handle into the side of your Upper Receiver with the holes to accommodate the wings on the Charging Handle.
  19. Then slide in the BCG and ensure the Gas Key sits on the side of the Charging Handle. Finally, push in both parts into the Upper Receiver all at once.
  20. You have a complete Upper Receiver Assembly.

Assembling an AR-15 Lower Receiver Assembly

  1. There is no specified manner to assemble your AR-15 Lower Receiver. In our case, we shall start by installing the Front Pivot Pin.
  2. Drop your Spring into a hole located on the upper and right side of your Lower Receiver. Then push in a Detent with your thumb on the same hole. Use a punch measuring the same diameter as your Detent will help you handle this small task.
  3. Push your Pivot pin against the punch and towards its slots until the Detent clickson the pin’s channel.
  4. Position your magazine catch on the right side of your Receiver on its respective hole. It will protrude on the right side of your Lower, and it allows you to drive a Spring and the Magazine Release Button to make everything intact.
  5. Fix in the Bolt Catch Assembly into the Lower Receiver.
  6. Drop the above assembly into its place and use a thin punch to keep the holes aligned. Go further and drive in a Roll pin into the aligned hole.
  7. Ensure your Bolt Catch works well and has spring tension.
  8. Fit in the Safety Selector into its slot on the left side of the Lower Receiver. Then the push in the Selector Detent into a hole near the grip guard.
  9. Next, you should place a spring into the pistol grip and join the pistol grip to the Receiver. Then tighten the two by driving in a screw on the bottom side of the pistol grip.
  10. After the installation, the selector should click into both positions.
  11. It’s time to install your buffer tube.
  12. Screw the Buffer Tube into the rear side of the Lower Receiver.
  13. Drop the Buffer Retainer and Spring into a hole located in the Lower Receiver’s front-rear parts where it joins with the Buffer Tube. Then hold down the Retainer and continue screwing until the buffer catches the edge of the Retainer.
  14. Drop in a Takedown pin into the right side of the Lower Receiver.
  15. Then insert a Detent and Spring into a hole between the grip and the Buffer Tube.
  16. Then tighten your Castle Nut on the Buffer Tube.
  17. Add your buttstock to the buffer tube.
  18. It’s now time to install your Buffer and Buffer Spring into the Buffer Tube.
  19. Attach the Disconnector Spring into the back of the Trigger. Also, join the Hammer Spring on the Hammer.
  20. Position the Disconnector on top of the Trigger.
  21. Then drop in the Trigger unit into the Receiver. Confirm that everything is aligned, and you can press in your Trigger pin. Use a roll pin punch to install the Trigger Pin.
  22. Finally, insert the Hammer and its Spring into its position in the Receiver. Also, alignment is critical to give space for a Hammer Pin.
  23. Confirm your Trigger is functioning.
  24. Now, you have a complete AR-15 Lower Receiver assembly.
  25. You should join your two assemblies, i.e., the lower and upper. They will make a complete gun.
  26. Then load your magazine with quality ammo ready to test how your AR-15 functions.
  27. The AR-15 has room for customization; thus, you can add accessories of your choice to your gun.


AR-15s are among the most common built guns and very popular rifles among shooters. They have proved to be reliable, accurate, and ergonomically designed kind of firearm.  Also, building your own AR-15 allows room for customization to suit your needs and preferences.

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