Military Style Title I Guns: The AR-15... The Ultimate Modular Rifle

By Jeff W. Zimba

In my humble opinion there is no rifle as versatile as the AR-15. There are an unlimited number of configurations possible, and an amazing number of caliber conversions, with more joining the ranks every day. One of the best features of this rifle system is that you can have almost every possible combination without ever having to buy another rifle. For the budget minded gun collector or for the person who just eventually gets bored with every gun over time and needs a new fix, the AR-15 is your dream gun come true. The mere purchase of one rifle, some basic tools and a small budget for “extra parts” now and then can keep your gun collection looking fresh.

The lower receiver is the part of this rifle that is considered by the Bureau of Alcohol, Tobacco and Firearms to be “the firearm”. This is the part the pistol grip is connected to and carries all the model information and serial numbers. In order to purchase the lower receiver, whether it is part of a complete rifle or as a stand-alone item you must fill out an ATF form 4473 (yellow sheet). If you wish to purchase a lower receiver from an out of state source you must go through a licensed gun dealer.

Every other part of the AR-15 can be purchased direct from dealers, distributors and manufacturers with no local dealer required. The other parts are not regulated. This being the case, that one lower receiver can be transformed into almost any configuration with a simple phone call to one of the several AR-15 parts dealers in this very publication. These new parts can be delivered directly to your home and assembled into your “new” rifle at your convenience.

After you flip through these pages and decide what you want your “new” rifle to look like, you are going to need to find a local RKI in the AR-15 field. (Reasonably Knowledgeable Individual is a phrase coined by Dan Shea back in the old days of Machine Gun News Magazine and makes reference to someone with an above average knowledge in their particular field without having to wear the “Expert” title or to carry any of the excess baggage that comes with that title.) It would also be wise to purchase some of the many books written about the AR-15.

Your next mission will be to obtain the tools necessary to disassemble your rifle from its current configuration and to install the new parts. Your configuration change can be very simple, as in changing only the furniture to go from the early SP1 look to the newer A2 style and this would requite far less tools than swapping barrels on your existing upper receiver. You don’t need to purchase every gunsmithing tool in one shot but you should look into the correct tools necessary each time you modify your gun.

If you are going to just swap furniture, all you really need may be a screwdriver, an allen wrench and a good strong handgrip. If you are going to buy a new upper receiver and leave the original lower receiver alone, you may not need any tools at all. If you are going to change out your trigger group to a newer 2-stage trigger, or add a new double wall gas tube, or re-barrel your original upper you will need a good set of punches, barrel blocks, special wrenches and lots of patience at first. If you are going to purchase a stripped lower receiver and assemble it from scratch to get started, you are going to need even more specialty tools to complete the assembly.

Everyone skimps a little on the correct tools at first but it is important to remember that you are working on a firearm here with a fair value. The correct tools will allow you to work on it with a minimal amount of problems and that translates into fewer scratches and other “whoop’s”. Having the correct tools also make the project much easier to complete. These tools are readily available from the advertisers in these pages and most of the regular AR-15 parts suppliers carry a full line of these specialty tools in inventory. They can also assist you in learning what tools you may need for each application.

When you are changing the configuration of your rifle it is important to remember that just because almost any part will interchange between guns, the final product may not be legal without prior registration with BATF, or it may not be legal at all. If you start out with a pre-ban “assault rifle” you can avoid many legal hassles associated with “manufacturing a post-ban assault rifle”. Just having the pre-ban rifle to start with allows you to purchase barrels with bayonet lugs and flash hiders. If you start with a post-ban rifle, it must remain in a post-ban configuration such as no collapsing stock, bayonet lug or flash hider. Most of the parts suppliers now carry almost identical parts kits that will fit either category to keep you on the right side of the law. Just make sure that you mention to the supplier which rifle you are starting with.

Another configuration problem you should be aware of is maintaining the correct legal barrel length. If you are starting with a 20” barreled, full size pre-ban rifle, you can buy a carbine parts kit and install a 16” barrel and collapsible stock but the barrel can not be shorter than 16”. Almost every parts dealer sells barrels and barreled upper receivers as short as 10”, and yes they would look pretty darn sexy on your new carbine, but this would change the status of your firearm to an illegal short barreled rifle. These short uppers are sold primarily as machine gun replacement barrels where barrel length is not an issue. Should you wish to install one of these on your semi-auto, pre-ban rifle you may do so, but you need to fill out a BATF Form 1 (see Small Arms Review Vol. 1 No. 10) and have it approved prior to ordering the short barrel. Without doing so the mere possession of the short barrel combined with possession of a semi lower receiver can constitute possession of an unregistered short barreled rifle.

If you should desire the look of a short barrel but don’t want the expense of registering the gun as a short barreled rifle you can always purchase the short barrel with a permanently attached flash hider that brings the total barrel length to over 16”. Permanently attached means just that, permanent. A little red Loc-Tite® will not do the trick here. Most are at a minimum silver soldered, and I always drill, blind pin and tig them just to be absolutely certain it is not coming off.

You also want to be aware of the differences between some problematic M16 parts that can be interchange with your AR-15 parts and also cause legal problems. Just as serious as the barrel length, the mere possession of an M16 trigger, sear, bolt carrier, hammer or disconnector combined with possession of a semi auto AR-15 lower can constitute possession of an unregistered machine gun. You don’t want to go there. Make sure you specify to the parts dealer that you are building a SEMI and again, whether it is a POST BAN rifle or a PRE BAN rifle.

The photos placed on the pages with this column represent just a small sampling of the many configurations possible to have with the same lower receiver. These photos were taken on a few different ones. Some of the hand guards or flash hiders don’t necessarily match the correct upper receiver’s to emulate originals, but you can build any combination you wish. The sky is the limit. Of course, there is no guarantee that you won’t like all the configurations and you even many want to own them all at once. This means several lower receivers and much more expense but, hey, who is sweating the details. We all have to start somewhere. Have fun and be safe.

Parts Sources

Cherokee Accessories

Cheek Pieces
2128 Farril Ave.
Dept. SAR
Union City CA 94587

424 W. Orchard Way
Dept. SAR
Gilbert, AZ 85233

Bushmaster Firearms
AR-15 Parts & Tools
999 Roosevelt Trail
Dept. SAR
Windham, ME 04062

AR-15 Parts & Tools
13983 Industry Ave.
Dept. SAR
Becker, MN 55308

J&T Distributing
AR-15 Parts & Tools
Box 430
Dept. SAR
Winchester, KY 40391

M&A Parts
AR-15 Parts & Tools
P.O. Box 32
Dept. SAR
Lake Zurich, IL 60047

Mounts and Rails
3602 E. 42nd Stravenue
Dept. SAR
Tucson, AZ 85713

This article first appeared in Small Arms Review V5N8 (May 2002)
and was posted online on January 24, 2014


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