AR-15 Pistol Build

It seemed like just when I started looking at the AR-15, prices went through the roof and everything was out of reach. In some ways, it reminded me of the old Johnny Cash song, "One Piece At A Time". Though I didn’t have access to parts on an assembly line, the idea stuck in my head. If I could find the parts—one piece at a time—I could assemble them myself, hopefully with better luck than the Cadillac in the song. Let’s start with the lower receiver.

Skipping forward a few years, I stopped at a gun show where they were selling $40 AR-15 lower receivers. Finding this too hard to pass up, I filled out the paperwork and left with a basic receiver. This is an important distinction. A plain receiver can be made into a pistol or a rifle, while a rifle receiver can only be a rifle unless you fill out more paperwork and pay more money. The lower receiver houses the fire control group, the magazine, buffer tube, and is where the upper attaches.

Except for the buffer, there isn’t a lot of major movement going on in the lower. As I was reading about assembly, most sources said that polymer lowers where best kept as rifles due to the added strain from the shorter gas system on the pistol. It was also recommended to use a lower made from 7075 T6 aluminum instead of 6061 for better long-term durability. Next came a squad automatic weapon (SAW) grip. I have tried the basic handle and found it to be rather small. I wanted something easier to hold.

Handles can be found in many different styles, sizes, and materials. The SAW grip felt OK and was twelve dollars, so I went with it. The next set of pieces was the lower parts kit. To make the lower receiver usable, the easiest thing to do is buy a complete parts kit. This will include pins, springs, trigger, sear, handle, and everything to make the lower receiver functional.

If you are going to change things (like using Wolff springs, a custom trigger, or ambidextrous safety) and you don’t want to have spare parts laying around, you will want to price individual parts and buy them that way. The end result was a receiver and grip that vaguely looked like a firearm but was not capable of doing anything. The search for parts continued. As I looked, I thought about the firearm I wanted to make.

Rifle versus Pistol As you search for parts for any AR build, you will have to decide whether you want a rifle or pistol and what caliber you want. A .223/5.56 barrel can be had in a 7.5" pistol-length to a 20" or longer rifle length with options in between. As the barrel length decreases, the amount of flash and volume increases. Other than that, it seems that the pistol would be compact and easy to handle.

The main difference is the barrel length; the upper receiver is the same length and the buffer tube is within a couple inches. Unlike an AK style pistol, the AR pistol will still need the buffer tube, unless you find one that operates by blowback like a 9mm upper. This makes for a rather large and somewhat unwieldy pistol in .223/5.56.

AGI Online Class It was during this time while contemplating my build options that I received an email from the American Gunsmithing Institute with an offer for their "Certified Law Enforcement Armorer" class online. The offer was too good to pass up, so I started the class. This version of the class was completely online. It consisted of watching videos, then taking a rather lengthy test at the end. Topics covered included design, function, assembly/disassembly, maintenance, cleaning, and different options.

It doesn’t matter how much a gun costs, what state-of-theart materials it is made from, or how "cool" it looks if it doesn’t function when it needs to. This is vital for any firearm but especially those used in law enforcement where someone’s life depends on it. Being relatively new to the platform, I was a little apprehensive taking the test

A hand stop, on the other hand, is necessary due to the short length of the barrel. but passed with a 90%. I would take the course again or take others in the price range. Pistol Choice Having weighed the advantages and disadvantages of a pistol versus a rifle, in the end the pistol won. There are a few disadvantages to an AR-style pistol. If you do not have a tax stamp, you can’t put a rifle stock on a receiver with a pistol upper; doing so makes it a short barreled rifle. Muzzle flash is greatly increased.

Muzzle blast seems to be best handled with ear plugs and ear muffs. A heavier buffer must be used to compensate for the shorter gas tube. These are countered by One is a 1/4" clevis pin, the other is designed for that purpose. the fact it is a rifle cartridge in a relatively portable package. As I mentioned, buffer tubes will vary based on your AR-15’s intended role.

While there are many styles of buffer tubes, the important thing for this build is that it is an explicitly-designated pistol buffer tube and not a rifle buffer tube. Adding a rifle buffer tube makes it an unregistered short-barreled rifle which is subject to legal problems. Some pistol buffer tubes are essentially basic tubes with foam on the end.

Others have straps so you can fasten them around your arm to allow you to hold on better, though they are more controversial and their legality seems to be tied to public and political opinion. This controversy also greatly affects the price and availability. I found a vendor at a gun show selling basic pistol tubes, springs, buffers at a low price and purchased one of each. The fastest way to complete a pistol build is to buy a complete upper and attach it to the prepared lower.

As with the lower, there are numerous companies selling numerous variations on the upper and its contents. If you are wanting something different, it may be more cost efficient to buy individual pieces and assemble them yourself. The best thing with a pistol is to buy a kit from a manufacturer and assemble it. Finishing out my parts acquisition one piece at a time, charging handles have many styles available. I picked a basic charging handle. It also happened to be the lowest priced one available.

For the bolt carrier group, there are also many different options available online while the offerings at gun shows (around here at least) are usually more limited. I was told by the seller that magnetic particle inspected (MPI) bolt carriers were the best to buy. Note that the firing pin retaining pin is a special, hardened pin and not a cotter pin—they are not interchangeable. Speaking of the firing pin, you can purchase a plain steel firing pin or a titanium version.

Some consider the titanium pin to be superior. Arma Lite doesn’t hide their feelings for the titanium pin having published Technical Note 2: Titanium Firing Pins Considered Generally Useless [Arma Lite’s Tech Note series were authored by the late Lt. Col. Mark Westrom, former owner of Arma Lite and Army Reserve Marksmanship Program commander, can be found free online, and are worthwhile reading for all AR-15 builders and aficionados.—Ed.] Though it reduces the possibility of a

slamfire, Arma Lite says in the Tech Note that titanium "doesn’t handle impact well." Some may have great success with them but I kept the steel firing pin. Many variations of forends are available. When you pick a forend and barrel nut, make sure you have the wrench that fits the nut. A quick count showed 17 different wrenches but there are probably many more. Starting torque for the barrel nut is 35 foot-pounds. The armorer’s class recommended that torque be increased until things line up as the nut is tightened.

I’ve found at least one company that sells washers to help with that. Barrels for a non-pistol AR-15 are easier to find than traditional pistol lengths. Though a pistol could technically have a 20" barrel, that would make it even more ungainly and awkward that it already is. Remember, as barrel length decreases, velocity decreases, especially with rifle cartridges. Muzzle blast also increases, possibly leading to some impressive displays as daylight fades. Twist rates are available for different bullet weights.

The particular barrel I used has a 1:7 twist rate. Chambers are available for .223, 5.56, and the Wylde variation. Note that headspace gauges are specific to the chambering. Many other cartridges, such as 9mm, are available, too. I looked for 5.56/.223 because I didn’t want to have to stock another caliber at the time. On the topic of vertical foregrips, though a rifle can have one a short pistol cannot unless it has been registered with the BATF as an "Any Other Weapon" category.

With the short barrel and my fondness for my fingers, a hand stop was mounted on the end. Since the bolt and the barrel are both cut to spec, the headspace on the AR-15 is determined by the barrel extension. A great resource for this is AR-15 Builder’s Resource by Jordan Edgar first published in 2006 and available for free download at GunsNet.net/manuals/BUILD- ERS_GUIDE.pdf. See page 31. According to that manual, if you buy quality parts new, you should not have any headspace problems after assembly.

Having completed the AGI course and wanting a full experience and also purchasing unknown parts from different vendors, I checked the headspace before initial firing. Gas tubes are available in different lengths based on barrel length. A 7.5" barrel requires a very short gas tube. Some use an adjustable gas block to help aid proper cycling. For sights, I chose a very basic "Walmart Special" red dot. I’ve had decent results with this model on a 9mm carbine and thought I would try one on my new AR-15 pistol.

Having been caught with a dead battery on the 9mm, I purchased a few extra but wanted non-powered sights as a backup. One of the tables at a recent gun show had spring-loaded backup sights at a good price, so I bought a set. Originally, I had bore sighted the pistol with a laser and then shot it at 10 yards, mainly to see if it actually worked. It worked very well, but then I added the backup sights. When I flipped up the backup sights, I couldn’t see them through the red dot scope.

This would mean removing the scope to use the backup sights or buying a riser to mount it on. Amazon had a riser at the right price and now the backup sights can be seen through the scope. Tools Some tools are necessary, and others are very handy to have on hand when you assemble an AR-15. A 5/8" long piece of 5/32" rod, whether cut off a drill bit or turned down on a lathe, can be used to hold the trigger, disconnector, and spring together in the receiver until you drive the regular pin in.

You can buy a tool to greatly aid in installing the front pivot pin or you can use a 1/4" clevis pin. If you prefer to make either of these, there are drawings in the Army manual TM 9-1005-319-23, which is available online. Real Avid (RealAvid.com, offers a multi-function bench block to assist with assembly and disassembly. It includes a place to set the bolt while you turn a screw to compress the ejector for removal. Sinclair International (SinclairIntl.com, also sells a bolt vise for this.

Geissle Automatics (Geissele. com, carries their Reaction Rod that holds the barrel while you work on it. There are also vise blocks to hold the receiver. Other companies sell their own version of either of those. A laser bore sight from a reputable manufacturer seems to work well for initial sighting. Some troubleshooting hints. With the hammer spring, check for an improperly installed hammer spring that won’t let the hammer strike the primer hard enough.

With carrier keys, they should be torqued to 35-40 inch-pounds and then double staked. If they loosen up, there may be cycling problems. Conclusion The AR-15 pistol in .223 is very loud and semi-practical. I have read that they can be very particular to cycling ammunition, especially if they are assembled from a variety of manufacturer’s parts. So far, I have only tried about four boxes of 55 grain Tula ammunition but it has functioned every time.

I haven’t had any problems with cycling or feeding and everything fit together without any "adapt-a-kits." The backup sights are good enough to hit pieces of clay pigeons that were left on the 50 yard backstop. I imagine I get odd looks as I carry a tennis racket case to the bench at the range but that’s the size of case it fits. It’s not a tennis racket… but it sure does make a racket! AG