Building an AR15: Checklist and Step By Step Guideline

Why buy a brand new AR15 from the gun store while you can build your own rifle at an incredibly lower price?

If you’re a gun enthusiast, you might have known by now that the AR15 features among the most popular rifles in the whole of the US. This is mainly based on the fact that it comes with unbeatable accuracy, superior modularity, and extreme flexibility.

But something you might not have known about the same rifle is that you can build it on your own- with all the necessary tools at hand- from start to finish.

Sounds exciting?

Well, in this post, I’ll take you through everything you need to know on how to build your own, full-functional AR15 rifle that’s customized according to your specific rifle needs.

Let’s get into the details right away…

BEFORE you begin building your AR15…

I know you’re truly excited to learn how to build your first AR15 and I don’t want to keep you waiting for the details. But before I roll the guide out, allow me to point out some crucial info you need to keep at the back of your mind before you begin this process…

  • Mind your safety: as you’ll be dealing with pins and springs which are capable of flying into your eyes, be sure to wear safety glasses before you start the job. You should also consider wearing a shop apron to help protect your clothing.
  • You’ll also need to consider your work area: ensure it’s well lit, clear, and clean. If possible, consider using a gun cleaning and maintenance mat to prevent your parts from getting lost (or to make it easy and quick for you to get the right part when needed).
  • The floor area: sometimes your smaller parts fall. And if you've got a clean and clear floor area, it’d be easy for you to locate them. So make sure your floor area is also clean.
  • Define your purpose of building the rifle: before you can set out to buy the various in the stores, it’s essential that you have a clear picture of the kind of rife you want and what you want to sue it for. This will enable you to customize your rifle according to your requirements.

If you plan to use your rifle for shooting, you’ll want to accommodate large house calibers.

If you intend to use it for competitive shooting, it should come with special trigger groups and longer barrels to enhance its accuracy.

And if self-defense is your priority, then you’d want to come up with a lightweight, compact with attachment options for laser sights and other gun accessories.

What to do you intend to use your rifle for?

Keep these four crucial tips in mind before setting out for the task ahead, and you’ll have an easy time building your rifle.

Tools & Parts Needed

In this project, you’ll need to acquire the right tools for the job. It’s important to note not using the right equipment might affect the quality of your rifle.

So, be sure to use the right tools ONLY.

The key tools to obtain include:

Parts Needed:

  • Bolts
  • Bolt cam pins
  • Barrels
  • Charging handles
  • Charging handle latches
  • Charging handle latch pins
  • Charging handle latch springs
  • Firing pins
  • Forends
  • Gas tubes
  • Gas tube roll pins
  • Gas blocks
  • Upper receivers
  • Ejection port covers
  • Forward assists

Tools Needed:

  • Bench vises and clamps
  • Gun cleaning/maintenance mats
  • Brass punches
  • Adhesive and solder
  • Torque wrench
  • Action block
  • Akedown wrench
  • Shooting glasses
  • Screwdriver sets
  • Loctite
  • Punches
  • Hammers
  • Roll pin starter punch
  • Cleaning utility brushes
  • Gunsmithing fixtures

Assuming you’ve all the above tools by your side, it’s time to start building your gun…

Step-by-step Instructions:

Step 1: Start by spreading out your gun cleaning and maintenance mat

Obviously, the first thing involves spreading out your mat and arranging all the tools and parts needed for the job on it. This will make it easy for you to access a particular item whenever you need it.

See also: ​Best Ar-15 Cleaning Kit For The Money: Reviews and Buying Guide​​​

Step 2: Install the forward assist assembly on the upper receiver

For this step, you’ll need to use a forward assist, forward assist spring, and the forward assist (roll) pin.

Turn your upper receiver with the upside down such that the Picatinny rail lies against the work surface.

Now slide in your forward assist spring on the forward assist (you can do this in any direction).

Then start your forward assistant pin into the bottom of your upper receiver so that it stands on its own. I recommend you to use a roll pin starter punch to drive hammers or punches on the least visible side.

Insert your forward assist assembly, ensuring the pawl is oriented toward the receiver middle.

Slide the entire forward assembly into the upper assembly. And with the assembly in a compressed state, push your pin through until it’s with the receiver. When the pin gets firmly started, you don’t have to continue compressing the assembly; instead, you can use a large brass punch to easily drive in the pin to a level where it’s barely sticking up.

When all is set, you’d want to test your forward assistant assembly to ensure its moving in and out freely when compressed.

Then move to the next step…

Step 3: Install the ejection port cover assembly on the upper receiver

For the successful assembly and installation of ejection assembly port on the upper receiver, you’ll need these items: Ejection Port Cover, Ejection Port Cover Pin, Ejection Port Cover Pin Snap Ring, and the Ejection Port Cover Spring.

Start by carefully placing your ejector port cover spring in the grove situated at the end of the ejection port cover pin.

Next, gently hammer your ejection port cover pin snap ring for the remaining way into the pin. It’s always advisable to make direct, down strike hammering on the ring, or else the pin might flaw away. Also, be sure to wear your safety glasses (just in case).

Now position your upper receiver on its side such that the ejection port faces upward while the barrel thread points to the right- while you stand over the receiver. Barely start your ejection cover pin so that it stays on its own, making sure to start the end without snap ring first.

Place your ejection port cover on upper receiver in the open position. Ensure the holes in receiver are lined up with those of the ejection port cover.

Slide the cover pin through the receiver hole that’s closest to the barrel threads. Stop right before the pin emerges in the ejection port cover’s central opening. This is where the cover spring goes.

With the cover spring in held your left hand, grab its longer part (the one sticking out) and wind it half revolution away from your body- stop when the long part points toward you.

With the spring under tension place, its long end on the right side of your ejection port covers closest to the pin- while its till held in your left hand. Then, slide the pin the remaining way through, until the snap ring blocks its progress.

Close the ejection port cover, and ensure it snaps shut.

Reach inside your upper receiver and push the ejection port cover, ensuring it snaps open.

Step 4: Assemble the bolt carrier assembly

For this part, you’ll require the bolt, the bolt carrier, bolt cam pin, firing pin, and the firing pin retaining pin.

Since the bold comes fully assembled and ready for installation into the bolt carrier, you’ll just need to push it all the way into the bolt carrier- ensuring the hole through the bolt middle gets aligned with the one directly under bolt carrier key. While still on it, ensure the bolt is in such a position that the extractor appears on its left side when you look at its (bolt) face.

Next, insert the bolt cam pin through the large bolt carrier hole. Ensure the pin holes are perpendicular to the bolt carrier key for a hassle-free insertion. Once the pin is fully inserted, try rotating it ¼ turn to get its large holes lined up with the back and front of your bolt carrier- to allow the firing pin to easily slide through.

Now slide the firing pin all the way down the bolt carrier until it stops.

You’ll then need to insert the retaining pin (with the skinny side first) into the left side of your carrier.

Be sure to test the bolt to see if it freely moves in and out of the carrier.

Step 5: Set up the charging handle assembly

As you can easily tell, this stage will require you to use the charging handle, charging handle latch, charging handle latch pin, and charging handle latch roll pin.

Start by inserting the spring into the charging handle.

Then start the roll pin into the top part of your charging handle such that is stands on its own. Using the roll pin starter punch for this job will make it even easier.

With the latch compressed into the handle, align the holes and then drive the roll pin until it’s flush.

That’s all you need to do to successfully set up the charging handle.

Step 6: Set up the charging handle assembly as well as the bolt carrier assembly into the upper receiver

This step signals complete setting up of the upper assembly by installing the bolt carrier and charging handle assemblies into the receiver.

However, you’ll have to remove these parts to easily install the barrel assembly (in step 9).

To insert the charging handle, turn your recover upside down so that its Picatinny rail lies against your work surface. Then insert the handle assembly by simply lining up its tabs with receiver interior grooves.

Slide the handle assembly inside as far as it stays stationary on its own.

Pull the bolt outside the carrier as far as it can go to ensure the bolt cam pin doesn’t contact the upper receiver inside. If you fail to pull the bolt, you’ll have a hard time trying to insert the carrier into the upper receiver.

Now insert the carrier system into the charging handle system, ensuring the carrier key rides in the trough located on the handle underside. Stop when the two systems appear even and parallel with each other.

The last step involves pushing the handle and carrier assemblies into your upper receiver until they firmly clicks into place. Note that the ejection port assembly ought to pop open during this step.

Step 7: Time to install your upper receiver into action block

For you to do this, you’ll first need to remove the bolt carrier and charging handle systems from your upper receiver.

When you’ve done that, grab the action block insert and slide it into the receiver back; the ejection port cover should pop open during this process. The purpose of the insert is to keep your upper receiver from getting easily crushed on tightening it to the vise.

Close the ejection port cover.

Place the receiver into your action block, and then close the block.

Place the block into the vise and tighten it into a snug (avoid overtightening though).

Step 8: Install the barrel as well as the outer receiver nut & barrel retainer nut on barrel threads

Fitting the barrel is as simple as sliding it into the threaded end of your receiver. While doing so, ensure that the slot on the receiver aligns with the pin on barrel. This will, you’ll easily slide your barrel all the way into the receiver until its pin hits the back of the receiver slot.

When the barrel is installed, your next would be to install the outer receiver nut as well as the inner barrel retainer nut on the threads of the barrel.

NOTE that the instruction for carrying out this particular process tend to vary from one handguard to another.

Depending on which type you’re using, your handguard manufacturer will provide you with the instructions to follow for proper installation.

Step 9: Setup the gas block and gas tube

Assembling the gas block and gas tube will require you to have the gas tube, gas block, and the gas tube roll pin at hand.

Begin by inserting the tube into the gas holes of the inner barrel retainer nut, upper receiver, and outer recover nut.

Loosen the screws on gas block base to allow it to easily slide over the barrel. And then slide the block down the barrel as far as it can go, as you guide the gas tube into hole in the gas block.

Ensure you lightly tighten the set screws on the block to enable it to stay in place while allowing the block to move freely

Set the block in such a way that the gas hole of the gas tube gets perfectly aligned with the barrel gas hole.

Tighten the set screws completely (but don’t over-tighten!)

Eventually, drive the gas tube roll pin all the way through the block and tube.

Once you’ve done that, you’re ready for the next and the final step in assembling your AR15 rifle…

Step 10: Finally, install the free float tube handguard

To complete your AR15 building process, set up your 6-32 x 1/8 " plug screws on the top part of the free float tube handguard.

You’ll then need to install the sling swivel studs into the handguard. You can do this by removing the swivel stud from the retainer nut and then placing it (the nut) inside the handguard track. Screw the nut swivel stud into the retainer nut- it's that easy.

Finally, align the handguard screw holes with those in your outer receiver nut, and then install the 6-32 x 5/16" flat head screws.

If you made it to this step, congrats! Your custom-built AR15 upper receiver is all set and ready for attachment to the lower receiver assembly!

Why Build Your Own AR15

If you think that buying a new rifle from the stores is way better than building your own, you’re wrong!

In this section, I’ll give you some amazing facts on why you should focus on building your own model from scratch…

  • It allows you to save a lot of money. Yes, making your own model will help you save a few hundred dollars that you can use for other important stuff. While a new rifle will cost you around $800 or more, buying the right parts for building a complete rifle will cost you between $500 and $600.

Isn’t that an easy way to save money?

  • You have the chance to customize your rifle as per your needs. In other words, you’ll be able to build the gun you want. Depending on your intentions of using the gun- whether you want to use it for hunting, shooting, or self-defense- you’ll have an easy time customizing its various parts to meet your expectations.

This is unlike the store bought rifle as they all come with the same style and appearance.

  • And, of course, this could turn out to be a great hobby for the DIYers. Embarking on assembling your own AR15 rifle is a great hobby that will keep you occupied for a couple of hours.

And you’ll indeed become excited when you see your final outcome- a fully functional AR15 assembled by your own hands!

Building Your Own AR15: FAQs

1. Do I need to register the AR15 rifle I’ve built on my own?

The Federal firearms registry doesn’t require you to register the gun, but the law might vary from state to state. California, for instance, requires you to register such a rifle. So, ensure you check what your state laws say on registering your own rifle.

2. Should I acquire a license for my custom-built rifle?

Unless you’re milling the lower receiver, you don’t need any license.

3. Any rules on building your own rifle?

Not really. The same rules for buying a factory made AR15 apply for building your own rifle.

4. Can I sell my custom-built AR15?

In general, the same law governing the private selling of guns will apply in this case as well. However, it’s important to check what your state laws state about such a case to be 100% sure, you know.

5. What procedure should I follow when buying my AR15 lower receiver?

While you can freely buy all the other AR15 parts, getting the lower receiver isn’t easy as it’s considered as a gun. That said, you’d want to undergo the procedures and necessities required of you by your state when buying a firearm.

If you’re buying from your local shop, all you’ll have to do is fill the Fed form like you’re buying a gun.

If you make an order online, then you’ll have to provide the seller with your local gun shop license so that the receiver will be sent there after making the payment. And when you go to collect your receiver, you’ll be required to fill the ATF form.

In my opinion, getting the receiver from your local gun shop is quite easier as you won’t have to undergo too many procedures.

Final Verdict

Building your own AR15 rifle might sound daunting and impossible at first. But it becomes possible and easier to do the moment you begin working on it. As I did mention in the last bit of this post, building the rifle on your own not only helps you save a great deal of money, but also allow you to customize your rifle to fit your specific shooting, shooting, or self-defense needs. Even better, it’s a great, fun learning experience.

With the step by step guide we’ve outlined in the above, I’m confident that you’ll be able to come up with one of the most popular rifles in the US. You don’t need any prior experience for you to successfully work on this project.

Just gather the right tools and follow the directions and you’ll be good to go.

And oh! Mind your safety and working space when working on this project.

Wish you luck!

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