Building your own AR

The expression ‘building your own AR’ connotes a number of different meanings primarily because, as a modular system, the AR
platform presents several ‘build levels.’ The least of these is the simple matter of picking the lower receiver you want, or can afford,
finding the upper receiver in the caliber and configuration you want, putting them together and pushing in the pins.

Things can get more complicated, of course, but they don’t have to. Even with this simple procedure there are some matters to
consider. All AR-15, AR-10, SP1 parts and accessories may be mailed to anyone in most states with the exception of lower
receivers and/or parts that contain a receiver, unless expressly forbidden by state law. There is no Federal law that prohibits it. Most
manufacturers and wholesalers will specify in the ad information which states prohibit a particular item.

All serial-numbered lower receiver housings must be shipped to an FFL holder.  Most small gun shop owners will receive lower
receivers for a small fee. Contact the proprietor first and make arrangements before you buy. Some may require you to buy the
lower receiver through them, if they are a dealer for the product line. And most gun shop owners will be glad to inform you of any
state or Federal prohibitions.

It is a good idea to find a dealer/owner that you like and establish a working relationship with him to keep fees low. Most are willing
to charge regular customers only a nominal fee.

Where to get what you need to build your own AR

For upper and lower receivers and other parts, after-market accessories and most anything you may need for your AR, go to the
following websites:

Upper/lower receivers and major gun components at retail

For gun parts and accessories, plus upper and lower receivers at clearing house prices

For guns, shooting supplies and ammo at discounted prices go to

Cautionary things to consider

Make sure the parts will fit. Some Colt lower receivers sport what is known as an ‘oversize hinge pin,’ a forward pin that is larger
than standard. Some early Colt lower receivers were made with this oversized pin to discourage civilian buyers from using other
competitive upper receivers. The problem is easily solvable however as many clearing houses offer a front hinge pin adapter to make
any Colt lower compatible with any upper receiver. Colt lower receivers also use larger diameter pins for the trigger group which
restricts trigger group interchanges to Colt products.

Build it Yourself by Mail Order:

See questions at Bushmaster about what lowers BM 450 uppers will fit at:


See Stag Arms uppers and lower receivers here:


“Lower halves” here:


An inexpensive alternative is to go to  and put together a rifle there. It looks like they have dropped  the
prices on their ‘uppers’ and ‘lowers’ and you can put together a rifle for about $550 plus fees, S&H, for around $600 total cost.
Prices subject to change.

At this site, move the cursor to the button marked “Category” and click the drop-down menu at “AR-15 upper and lower
assemblies.” Then have fun deciding.

Other possibilities:

For “Pistol Caliber Upper Receivers” go to the following:


Basic Tips:

1.        There are two basic sizes of lower receivers—a short receiver group for .223 length cartridges and a longer (A10) length
receiver for 7.62X51-length cartridges. Uppers and lower receivers are not interchangeable between these two basic sizes; but with
few exceptions (see note above on early Cold lower receivers), .223/5.56 uppers and lowers are interchangeable. There is no
standardization in .308/7.62x51 models. Once you choose a proprietary model, you will have to get all parts from that manufacturer.
2.        All parts, add-ons and after-market accessories such as replacement barrels, sights and even complete upper receivers can
be shipped by mail without FFL.
3.        Any lower receiver housing or component attached to it will have to be shipped to an FFL holder.
4.        In many cases, depending on the components you choose, once you have paid for shipping, handling and fees, you may not
have saved a great deal of money; but, you will have saved yourself the frustration of having to shop from store to store and you
will have gotten the exact features you wanted on the firearm, for a price you thought affordable.

Good luck. Remember that at each website there is usually a menu button that tells how to contact manufacturers or others who
can answer your questions about their products.

Are All AR's Created Equal?

Those who work in retail gun sales are continually asked "What's the best AR?" And, if they are honest, it is a question almost
impossible to answer.

First, the answer is almost totally subjective in nature. As with beauty, 'the best AR' is largely in the 'eye of the beholder.' Final
choices are based either on the most expensive/least important aspect of choice -- fit and finish -- or, what is largely the most
common deciding factor, lowest price. They are not necessarily mutually exclusive nor, in practical terms, are they the most
important deciding factors.

The fact is that few AR's are actually built by the manufacturer whose name they bear. They are, in fact, assembled from parts
manufactured by other companies. Here's the list of finishers and manufacturers:

As of February 2008, the manufacturers of the various AR receivers are the following:


Continental Machine and Tool (CMT): Colt, RRA, Stag, High Standard, Noveske, Century (current), Global Tactical, CLE, Smith
and Wesson, MGI, Wilson Tactical, Ratworx; http://

Lewis Machine and Tool (LMT): LMT, Lauer (old), DS Arms, PWA, Eagle, Knight's Armament, Barrett, Bushmaster

L.A.R Manufacturing: Grizzly, Bushmaster (L Prefix), Ameetech, DPMS, CMMG, Double Star, Fulton Armory

Mega Machine Shop (MMS): Mega, Gunsmoke, Dalphon, POF (forged), Alexander Arms, Stinger, Spike's Tactical (old)

JVP: Double Star, LRB

Olympic Arms: Olypmic Arms, SGW, Tromix, Palmetto, Dalphon, Frankford, Century (old)

Sun Devil: Sun Devil (forged billet)

Superior Arms: Superior Arms, Lauer (current)

2. Only three machine shops mill the majority of AR-15 receivers, likewise only a handful of foundries make the raw forgings:

Cardinal Forge Company
Cerro Fabricated Products
Anchor Harvey

Source:; retrieved 102312, 10:23am.

Manufacturer/Retailers (build most major parts inhouse)



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Acoustic Box
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.308 Winchester
The AR15—Universal Platform
Universal Shooter: Bullet Catcher

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