Featured How to build an AR-15 - thearmsguide.com

Published on July 6th, 2013 | by Nate Schultz (nsz85)

64

How to Build an AR-15: Beginner’s Guide

You do not always have to go to a gun store to purchase an AR-15. Surprised? I know I was when I first ventured into the hobby of building custom AR-15s. Some of you may not know, but building your own AR-15 is actually quite simple. However, if you do not know anything about the process, or where to start, you have come to the right place. I am going to start this “How to Build an AR-15″ series off with a list of frequently asked questions that I receive from individuals starting out with the hobby and possibly wanting to build their first AR-15.

Building an AR-15 FAQ

Q: Are there any rules or laws for building my own AR-15?
A: Only the same ones that apply to purchasing a factory assembled AR-15 in your state.

Q: Do I need to register my AR-15?
A: There is currently no Federal firearms registry, but you’ll need to verify the registry laws by state (e.g., New York does require registry of “assault rifles,” including standard AR-15 rifles).

My AR-15 - thearmsguide.com

Me smiling after taking some of the first shots with the first AR-15 that I built for myself. Photo of me courtesy of paul-vincent.com

Q: Do I need to be licensed or be a gunsmith to build my own AR-15?
A: Not unless you’re milling the lower receiver yourself.

Q: How many AR-15s can I build?
A: As many as you would like to—whichever comes first.

Q: If I build an AR-15 for myself, can I then sell it?
A: The same laws for private sales of firearms apply to selling AR-15 rifles. Check your state laws.

Q: How do I buy a “stripped” or “blank” AR-15 lower receiver?
A: You will need to find a dealer that sells AR-15 lower receivers. Said dealer can be local to you, or online.

Q: Can I buy all the parts online and have them shipped to my home?
A: This is a long one, so get comfortable. Yes and no. All of the components for your AR-15 build can be shipped directly to you at your home except the lower receiver.

The AR-15 lower receiver is the only component that is considered the “gun”. Therefore, when purchasing a lower receiver for your AR-15 build, you will have to go through the same channels as when purchasing a firearm in your state.

For example, in my state of Minnesota, if I order a stripped AR-15 lower receiver online, I will have to provide the seller with a copy of an FFL (Federal Firearms License) and the address to aforementioned FFL. In other words, I just have to call my local gun shop and ask them to fax a copy of their FFL to the seller. The seller will then collect money from me for the receiver, and then ship it to my local gun shop. When the gun shop calls me to tell me that my lower receiver has arrived, I will go there and fill out the ATF form to make sure I can legally own a firearm, pay a transfer fee (this fee is usually less than $30), and take my new AR-15 lower receiver home (thankfully, Minnesota has no waiting period for long gun purchases).

If I decide not to order online, and I know of a gun shop that stocks lower receivers nearby, I can just go purchase it directly from that store, and then fill out the necessary ATF form, just as I would for purchasing any other kind of firearm.

Q: What parts make up an AR-15 that I would have to purchase to build one?
A: There are a variety of different types of AR-15 builds, so this list will not work for all builds. However, I put together a list of components for building a typical M-4 style AR-15 with a stripped lower receiver, and stripped upper receiver:

  1. AR-15 lower receiver.
  2. AR-15 upper receiver.
  3. Lower receiver parts kit.
  4. Upper receiver parts kit.
  5. Lower receiver extension (aka: the buffer tube).
  6. Buffer.
  7. Buffer spring.
  8. Barrel & gas block/gas system (a carbine length gas system would be typical for this build).
  9. Handguards (length will depend on what length gas system you chose on your barrel: carbine, mid-length, or rifle).
  10. Bolt carrier group (carrier, bolt, firing pin, cam, extractor, ejector and spring).
  11. Collapsible (or fixed, if you prefer) buttstock.
  12. At least one magazine (be sure to check your state laws for magazine capacity limits).

Q: What is the difference between a forged lower receiver and a billet lower receiver?
A: With a forged lower receiver, the metal is “smashed” into the desired form while it is red hot. This compresses the metal and makes it very strong.

Billet lower receivers are machined from a single block of metal and tend to have a more custom, aesthetically pleasing appearance to some. It also tends to have the trigger guard built in, meaning it is not removable. They also tend to cost considerably more than a forged lower. Billet lowers may not have quite the tolerance that forged lowers, but by no means are they to be considered “weak.”

MEGA Billet Lower - thearmsguide.com

This is an example of a billet AR-15 lower receiver. Image courtesy of megaarms.com

MEGA Forged Lower - thearmsguide.com

This is an example of a forged AR-15 lower receiver. Image courtesy of megaarms.com

 

Q: How do I know which lower receiver to purchase? What “brands” are good?
A: There are a tremendous amount of different lowers out on the market, but not every lower is made by the company that has its name on the side. You would be surprised at how many lowers from different companies actually come from probably less than a dozen machine shops.

At present, this is the list of which manufacturers produce lowers for which companies:

Lewis Machine & Tool

  • LMT
  • Lauer
  • DS Arms
  • PWA
  • Eagle
  • Armalite
  • Knights Armament
  • Barrett

Continental Machine Tool

  • Stag
  • Rock River Arms
  • High Standard
  • Noveske
  • Century (New)
  • Global Tactical
  • CLE
  • S&W
  • MGI
  • Wilson Tactical
  • Grenadier Precision
  • Colt

LAR Manufacturing

  • LAR
  • Bushmaster
  • Ameetec
  • DPMS
  • CMMG
  • Double Star
  • Fulton Armory
  • Spike’s Tactical

JVP

  • Double Star
  • LRB
  • Charles Daly

Mega Machine Shop

  • Mega
  • GSE
  • Dalphon
  • POF
  • Alexander Arms

Olympic

  • Olympic
  • SGW
  • Tromix
  • Palmetto
  • Dalphon
  • Frankford
  • Century (Old)

Sun Devil

  • Sun Devil forged billet receivers

Superior

  • Superior Arms
  • Lauer (New)

Aero Precision

  • Aero Precision

Considering that almost all AR-15 lower receivers are made to a very specific tolerance, based on military specifications (mil-spec), my advice is to choose whichever AR-15 lower receiver that has a roll-mark (or logo) that you think is “coolest” or is most appealing to you personally.

Q: Some barrels say they are chambered in 5.56 and some say they are chambered in .223. What is the difference?
A: Basically, the rule of thumb is this: a rifle chambered for 5.56 can shoot both 5.56 and .223 ammunition. A rifle chambered for .223 can only shoot .223 and not 5.56. For the full story on 5.56 vs. .223, check out this article by Destinee.

Q: What does barrel twist mean? 1:7 and 1:9? Ratio? What?
A: Confused? Yeah, this one is kind of technical but I will keep it simple. When choosing a barrel twist ratio, you will want to choose one that best matches the type of ammo you would normally be shooting. What the ratio means, such as 1:7 for example, is that when the bullet travels down the barrel, it will make one complete spin (via the rifling) every seven inches.

AR-15 1:7 vs 1:9 Ratio - thearmsguide.com

(Fig. 1a)This is great information about shooting 1:7 vs. 1:9 twist ratios at long distances through your AR-15.

This is one of the most hotly debated topics about AR-15 rifles. Personally, I chose to go with 1:7 because it gives me the option of shooting the heavier rounds. Because 55gr .223/5.56 is the most common bullet weight available (that’s the weight used in XM193 military ball 5.56×45 ammo), and the most frequently fired, you would be fine with either 1:7 or 1:9. I have also been told by reputable sources in law enforcement that 1:9 is recommended for plinking, and 1:7 for hunting and home defense.

To break it down, 1:7 will do just fine with shooting lighter and heavier rounds. 1:9, on the other hand, will handle lighter rounds better, and will not do so well with anything heavy at long distances. (Fig. 1a)

Carbine vs Mid-Length vs Rifle AR-15 - thearmsguide.com

A comparison photo of different length gas systems, barrels and rail systems for an AR-15. Image courtesy of laruetactical.com

Q: What does carbine, mid-length and rifle length mean when choosing a barrel?
A: It simply means where the gas port in the barrel is placed. It is also sometimes referred to as the “gas-system”. Carbine and mid-length gas systems tend to be on barrels of 16-18 inches and shorter, while barrels with a length of 20 inches and longer will have a rifle length gas system.

It is important to know what length gas system your barrel has because the gas tube you purchase will need to be the right length in order to fit properly. For example, you cannot fit a carbine length gas tube onto a barrel with a rifle length gas system. The gas tube will be too short.

Q: I am ready to build my AR-15 lower receiver but I do not know the steps. How do I do it?
A: Great question. In the following posts in this “How to Build an AR-15″ series, I will go over how to build your AR-15 (starting with building your lower receiver, and moving from there to the AR-15 upper), what tools you will need, and I’ll offer some helpful tips along the way. Stay tuned.

About the Author

Nate Schultz is employed within the field of Law Enforcement, is an avid shooter, firearms enthusiast and hobbiest gunsmith. When he is not writing for The Arms Guide, he is producing content for his YouTube channel: www.youtube.com/nsz85


63 comments
42Coop42
42Coop42

I am new to ARs'.. Can I use a model 1 sales 6.8 SPC upper half and put it on a stag arms 6.8 SPC lower half? Will this work, or do both halves need to be the same brand?

JimmyChadwick
JimmyChadwick

I have completed my AR 15 lower. What are the initial steps that should be taken to start the upper? 

thederdog
thederdog

Thanks, can I build a AR-10 in the same fashion as a AR-15 ?

thederdog
thederdog

Is there a AR-15 built in 7.62

Sam Freedom
Sam Freedom

Absolutely amazing article.  This is not kinda what I was looking for... it's *exactly* what I was looking for... god bless you, Nate..

JMendez
JMendez

Is there a link for part2?

JTMako
JTMako

Nice write up. Thanks for taking the time & effort to put this out there.

HugeFan
HugeFan

Be careful new comers: Building AR's becomes a hobby... a disease. They're so adaptable to the desire of the shooter that your "first build" will never actually be completed not will it be your last. The good news is that you don't really need more than two or three lowers(SBR's will need a stamp as NS mentioned) because you can just build all sorts of uppers that will just bolt on to your lower. It's a thing of beauty. There will always be new rails, triggers, sights, etc. that will slowly erode your bank account into something that used to stand for fiscal responsibility.

JunkfoodZombie
JunkfoodZombie

To make one very important point ...... There ARE places where you must register your AR-15 "assault rifle." The NY "SAFE" act (safe, my a**) will require everyone in NY to register their ARs by a certain date this (or next) year. It would be wise for everyone to check their local laws about registration. Here in TN, I do not have to register hamdguns, but my family in NY does. Don't risk getting thrown in jail. Check your local laws!

Rev2DaLimit
Rev2DaLimit

The break down of where "naked" lowers come from is so helpful. I've wondered about that before. I was aware that a lot of them were made in the same place but hadn't seen them all catagorized by machine shop before. Nice!  

FateofDestinee
FateofDestinee

I seriously wish I had read this when I was building my first AR last year.

chyldeorchid
chyldeorchid

will any of the future installments touch on 0% or 80% lower receivers?

Nate Schultz
Nate Schultz

@palmer It sure looks like it to me, but that is also an 80% lower receiver so you will need a jig and a mill or a machine shop nearby.

Nate Schultz
Nate Schultz

@42Coop42 The upper and lower receivers do not have to be from the same manufacturer. Typically, if they are from the same manufacturer, the fit will be better but as long as they are in spec, you should be just fine.

Nate Schultz
Nate Schultz

@JimmyChadwick I have an entire series of articles covering how to build an AR-15 from start to finish. You will just have to search this site for what you are looking for :)

Nate Schultz
Nate Schultz

@thederdog I have not built an AR-10 style rifle yet so I cannot tell you for sure one way or another. Sorry :(

JunkfoodZombie
JunkfoodZombie

Which 7.62?

7.62x39? Yes, but not all that common.

7.62x51? Yes, that would be the AR-10 platform.

Nate Schultz
Nate Schultz

@JMendez It usually shows up in the related articles section, if not just search for it up at the top of this page :)

Nate Schultz
Nate Schultz

@Tyler0587 It's on this site. You may have to search for it at the top of this page or visit my author page.

thederdog
thederdog

The adaptability is the main reason for my choosing the AR-10. Actually looking forward to my first build.

AdamHo
AdamHo

@JunkfoodZombiewhat they dont know wont hurt em. remember....registration leads to confiscation in EVERY case. It just lets to gun grabbers know where the guns are.

Nate Schultz
Nate Schultz

@JunkfoodZombieYes, this is correct. It is everyone's responsibility to know the laws of their state. I could have worded it better, but I was referring to the fact that there is no national registry.

JunkfoodZombie
JunkfoodZombie

Notice "assault rifle" is in quotes because it's a BS term for ARs..........

Nate Schultz
Nate Schultz

I knew it was something I always would've liked to know when starting. I am glad you found it helpful :)

Nate Schultz
Nate Schultz

I will take that as one heck of a compliment, Dest. Thank you! I hope people will learn all they need to know through reading this series.

Nate Schultz
Nate Schultz

I am not saying that I won't touch on that topic, but as of right now I am not very experienced or well versed on it. We shall see what the future has in store. Stay tuned :)

thederdog
thederdog

Already completed the lower for my AR-10. Pretty much the same as a AR-15.

thederdog
thederdog

Thanks, just got my AR-10 lower, and colt trigger. Upper is on it's way. Appreciate everyone's help

thederdog
thederdog

Can I build a AR-10 in the same fashion as a AR-15

HugeFan
HugeFan

I've built only six (two of which are mine) but with each build your able to develop shorthand techniques and functional improvements that make the hobby as fun as shooting the rifle itself. I wish you both good luck!

Beardthirty
Beardthirty

And "AR"doesn't even mean Assault Rifle. A huge misconception with the AR. It actually means Armalite Rifle,which comes from the first manufacturer of the rifle.

SBRsrule
SBRsrule

@JunkfoodZombie we'll its a good thing that they are assault weapons and not assault rifles,,,,unless you have select fire,  semi, burst, full. just semi and safe is not select fire, so in term NOT assault rifle. New York SUCKS and Bloomberg can kiss my ass. I'm glad I don't live there.

chyldeorchid
chyldeorchid

I only ask because I have my first 80% lower on its way as soon as 2AM Arms finishes their materials test & have very little idea what to expect.

JunkfoodZombie
JunkfoodZombie

Any time. You can check out my YouTube channel. It's JunkfoodZombie. (One word). I try to put a variety of stuff on there and much of it is geared towards helping other people. Good luck with the build!

thederdog
thederdog

Thanks a ton, really appreciate your help.

JunkfoodZombie
JunkfoodZombie

Depends on what weight bullets you plan on shooting. A 1:12 twist is good for 170 grains and below. A 1:10 is better for heavier bullets and 1:11 is a good compromise. Any twist will shoot any weight but each twist is going to shoot certain weights more accurately than others. I would suggest doing some research to see which twist is best for the bullets you plan on shooting. Good luck!

P.S. .30-30 rules!

thederdog
thederdog

In the 7.62x51, what twist would you suggest. I have been a pistol guy most of my life. Moved to Washington and now am starting to see a need for rifles. Purchased my first rifle (Winchester 30/30) a few weeks ago and have enjoyed it more than I thought iwould. So I am pretty green with my knowledge on rifles

JunkfoodZombie
JunkfoodZombie

Yeah. It's basically the same rifle with sime larger parts. 7.62x51 was the original caliber for the M16 platform, It was the AR-10 first. It was quickly changed to accomodate the 5.56x45 round and dubbed the AR-15, then the M16.

HugeFan
HugeFan

Yeah, it's great for blue printing potential builds. Glad I could be of some assistance.

thederdog
thederdog

Gunstruction is awesome! Your right, it is pretty cool

HugeFan
HugeFan

Look up "Gunstruction". It's a design site where visitors can virtually construct rifles to their liking. It's pretty damn cool!

JunkfoodZombie
JunkfoodZombie

You can probably find plenty online. Same parts as an AR 15, only differences for the most part are dimensions and specs. Should be easy to find. Some parts are common to both like triggers and safety levers, while others like the lower receiver and bolt carrier are not interchangeable.

Sam Freedom
Sam Freedom

Are there parts lists freely shared by other users fur builds they have made or do ppl guard their creations with all their might? Like making anything, id like to gather everything first. And rather than start from scratch, maybe I could look over some others have made...

chyldeorchid
chyldeorchid

@Sns77 That's correct, but if you have the Jig, the drilling/milling isn't too difficult, and you end up with a firearm that you MADE yourself, not just assembled.

Sns77
Sns77

Pretty sure that you have to do the milling/drilling yourself. Whomever does the work becomes the manufacturer of the firearm, and cannot transfer it legally.

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