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Build a 9mm AR-15: cheap and cheaper! Part III.

In this final installment, Matthews completes his budget-busting 9mm pistol build and takes his pair of projects to the range.

In the last installment (Part 2), I made a pile of parts on the lathe, mainly parts to make a 9mm Suomi barrel fit. Now I'll get on with it and finish up this 9mm AR-15 pistol.

Once the barrel is done you can slide it into the receiver and install the barrel nut. Do not torque the barrel nut down very tight at this point because you may need to remove it later to polish or modify the feed ramp. Later when you have bench tested the gun for functioning you can install the nut to final tightness. When you do get around to permanently installing the barrel there is a recommend way of tightening the nut. Since this project has no gas tube, installation is much easier. Slide the barrel into the receiver and make sure it is fully seated against the front of the receiver. Apply some heavy grease to the receiver threads and to the front edge of the flange to make tightening easier and to prevent galling of the soft aluminum threads. Screw the barrel nut on hand tight.

To tighten the nut you will need a special wrench. You will need a general purpose AR-15 assembly tool or a GI barrel nut wrench. Prices for these tools can be as low as $10 for a GI-type barrel wrench and combination tool to as much as $50 for a multi-purpose tool made by some of the big name AR-15 gunsmithing suppliers. I have several tools but for this job I used my DPMS AR-15 multipurpose tool that cost about $30 from many sources. In this case you need the proper tool because improvised tools will likely damage you barrel nut. The DPMS multitool, and most other brands, feature two or more pins that engage the notches or holes in the barrel nuts. Place the tool into the barrel nut and tighten it down to about 15 foot-pounds of torque. Once tightened you then loosen it. Now you tighten it again but this time tighten it to about 25 ft.-lbs. of torque. Now loosen it again. The barrel nut can now be tightened town to a final torque of 35-50 ft.-lbs. Supposedly, this three-stage tightening and loosening allows the nut to seat better on the threads. It is the recommended procedure although GI torque specs are higher than those listed here because a steel barrel nut is used on GI-format guns. Exact torque is not too important because GI torque specs are 35-75 foot-pounds. This wide range is to allow you to align the notches in the handguard and allow passage of the gas tube. Because I have used a torque wrench a lot in the past, I typically just guess on torque settings and for go using a torque wrench.

Once the barrel nut is installed, I screwed my handguard to the nut. The round handguard can be difficult to grip and tighten. If you need a better grip to tighten the handguard further, you can use an inexpensive strap wrench to grip the handguard. These can be bought for less than $10 from stores and websites like Harbor Freight. You can also use a little removable liquid thread locker (such as Loctite #242) on the threads at final assembly to keep the handguards tight on the nut during use. Just be aware that if you use thread lockers disassembly can be difficult. Thread lockers are basically high strength glue and if applied correctly they are extremely strong.

To finish my upper receiver assembly I needed to do a couple more small jobs. Although not required for good operation, I installed a door assembly and a rubber 9mm case deflector. These were purchased from JSE for about $15. Unfortunately I had to remove the case deflector later during test firing. For reasons unknown the deflector deflected certain brands of ejected cases right back into the gun. This resulted in an immediate stoppage with a smashed case wedged in between the bolt and rear of the barrel with the new round about half way out of the magazine. This occurred with one brand of ammo only but it was one I would be using a lot. When I removed the deflector functioning returned to 100%. With the case deflector installed fired cases were being dropped right at my feet when they didn't jam up. With no case deflector ejected cases were thrown forcefully about 6 feet to my right and about 3 feet forward. I prefer to have 100% functioning rather, than having cases conveniently dropped at my feet.

Because this gun featured a 9mm bolt that did not have forward assist notches, I had no need for a forward assist button. I did not want to buy a regular button if I wasn't going to use it. Dummy buttons can be purchased but I did not want to spend money for one. I therefore made my own for free. I just took a 1/2" bolt and turned it into a dummy button on my lathe. This is just another example how home gunsmithing can save you money. That expensive lathe pays for itself every time I make my own parts.

I used an inexpensive surplus charging handle for this project. Since the handle only cost me $101 decide to add an extended handle release. This $8.99 part was bought from CDNN and installs simply by driving out a roll pin and substituting the new release. With the upper done, except for testing and applying a final finish, it was time to turn my attention to the lower receiver assembly.

Before going on to lower receiver assembly there are some things I should mention to novice AR-15 pistol builders. This concerns the legal aspects of the AR15 lower receiver. Since this project was a pistol I used a virgin receiver. A virgin receiver is a receiver that has never been assembled into either a pistol or a rifle. This is required per BATFE regulations. It is illegal to use a rifle receiver to build a pistol. If you use an existing rifle receiver to build a pistol you would be creating what the BATFE calls a short-barreled rifle (SBR). SBRs are highly regulated by the BATFE. A SBR must be registered with the BATFE, a $200 tax must be paid, a background check needs to be run and lengthy paper work must be filled out. After waiting for several months the BATFE finally gives approval for you to possess it. Failure to follow the rules is a Federal felony punishable by up to 10 years in prison and a $10,000 fine. To create a legal AR-15 pistol you must use a virgin receiver or an existing pistol receiver. To be considered a virgin receiver the receiver must have never been assembled into a rifle or pistol. This means ever in its lifetime. If someone assembled it into a rifle 20 years ago and then took it back apart and put the bare receiver on a shelf it is still a rifle receiver regardless of its present condition. Once a rifle, always a rifle. The best way to be sure you are getting a virgin receiver is to buy a brand new receiver of recent production from a licensed gun dealer. This way you are sure of what you are getting. You should avoid buying a virgin receiver from an unknown individual. The private seller may tell you it is a virgin receiver but can you trust them? Some people will tell you anything to make a sale. Even if the seller is being truthful does he really know the history of the receiver ever since it was first made? If they bought it secondhand it could have been in rifle format sometime in its past and they would have no way of knowing that fact. If a Federal trace was run on the receiver and it came back as formerly being a rifle you would be guilty of a felony. Saying that the seller assured you that is was a virgin receiver would be a poor defense to felony charges. You are responsible for the legal status of the receiver not some past owner or the seller.

The other option to create a legal AR-15 pistol is to buy a new pistol receiver from a licensed dealer. Some AR receiver makers offer AR-15 receivers that are actually classified as pistol receivers. This is due to the fact so many hobbyists are now making AR-15 pistols and some manufacturers want to cater to that market. The same cautions about buying a receiver in a private sale apply to pistol receivers also.

Your safest bet is to simply buy a new receiver--whether a virgin receiver or pistol receiver--from a licensed dealer. There would be little financial incentive to buy a used receiver because they are so inexpensive at this time. There are a few legal exceptions concerning the status and definition of an AR receiver but there is no reason to consider anything other than brand new receiver that has been sold by a licensed dealer. By the way, when you make out the form 4473 at the point of sale the receiver is listed on the form as a receiver only, not as a rifle or pistol. If it is a stripped receiver it cannot be a rifle or pistol because it has never been assembled into either form. The fact that some manufacturers are offering stripped receivers classified as pistol receivers even though they have never been assembled as a pistol is something of a gray area in the rules. I don't know how they are offering them as pistol receivers unless they have received a rule variance from the BATFE.

I used a budget priced Anderson AR-15 receiver for this project. I used the version that features an integral trigger guard. I prefer this type and they cost no more than a standard receiver. While these great receivers are offered for sale in the $60-$90 price range by many vendors it you look hard enough you can find them under $50 like I did. No matter if you buy a first-rate receiver or a cosmetic defect receiver you are getting a great MilSpec receiver from Anderson

Installing my $29.99 lower parts kit (LPK) is so easy I won't bother explaining it here. There are plenty of diagrams available in catalogs or online that can show the novice where the parts fit. Installing the LPK will take less than a half-hour.

Because this is a pistol project I used a pistol buffer tube. A pistol buffer tube has no provisions for fitting a stock. It will be completely round and will not have the rib on the bottom that holds the stock in correct alignment. Because the pistol tubes are round, they simply screw on in any position and don't have to be indexed. There are many lengths of pistol buffer tubes and the diameters can vary between brands. Unlike rifle buffer tubes there are no standards for size. The interior lengths of all models will be roughly 7 inches but the exterior lengths can vary as much as a couple inches. The tube I used had an exterior length of 9 inches. Many pistol buffer tubes, mine included, feature a knurled portion near the front. Many also have a ring or collar that functions as a stop if you are installing a SIG-Tac brace. The SIG-Tac brace is so popular than there are many buffer tubes made specifically for installing a brace.

Pistol buffers just screw into the rear of the receiver and are locked in place with a regular carbine stock lock ring. Remember when you install the buffer tube to first install the rear take down pin, the detent and spring into the back of the receiver. You also have to install a receiver end plate because that retains the detent and spring. The tube screws in till it is flush or just slightly below the front edge of the threaded receiver ring. Before screwing the tube in to full depth you have to place the buffer detent and spring in its hole in the bottom of the receiver. The tube screws in far enough to keep the detent from coming out of its hole but still allow the short tab on top of the detent to raise high enough to keep the buffer in the tube. You use a carbine stock lock ring wrench to tighten down the lock ring. These can be bought for just a few dollars and will prevent you from marring the lock ring if you try to improvise a tool. To help secure the buffer tube and lock ring, I put a dab of thread locker on the buffer tube threads. Only use a limited amount of thread locker such as Loctite #242. If you use too much it may run down into the buffer detent hole and solidly lock up the detent. I only apply thread locker to the last couple threads from the rear side so that I don't have worry about it running into the buffer detent hole. Make sure you use a removable type thread locker. High strength lockers can glue the parts together almost permanently. If you use too much or the wrong type of locker the only way to get the tube out of the receiver will be to heat the tube and receiver with a torch and that will not do any good to either part.

Once I had my pistol buffer tube installed, I installed a standard M4 carbine buffer spring. It seems that everyone has their preferred spring for the buffer. Some use special high strength springs while others go with standard springs. I had good luck with a standard $3 M4 buffer spring. It worked and fit the budget; what more could I ask for? After the spring went in I slipped in a special 9mm buffer. This one was 5.3 ounces where as a standard buffer is about 3 ounces. There are a wide variety of special heavy buffers made for 9mm ARs and they can get expensive. Some people report that they needed a special weight buffer to make the gun run right but I had good luck with the PSA 9mm buffer. It was cheap ($15) and it worked. That's all I could ask for in a buffer. Prior to installing the spring and buffer, apply a thin coating of oil to each part. Lubrication will allow the parts to cycle smoother and reduce wear on the tube.

Once I had my buffer tube installed it was time to install my bargain priced Century marked SIG-Tac brace. I immediately found out why it was so cheap. The hole in the brace was way too small to fit over the buffer tube. It was so tight that I could only get it on about an inch. Apparently this was the manufacturing defect that resulted in the extremely low price. Fortunately this problem was correctable. I took a large wood dowel and wrapped it with course sand paper. I slid the sand paper dowel into the hole and spun it with an electric drill to sand the hole to a larger size. The material of the brace was very tough and it took quite a bit of sanding to open the hole up enough that it would slide over the tube. Considering that a new brace cost $125 I figured 15 minutes of sanding was more than a fair exchange for the cost savings. Once I reworked the $25 reject brace it looked and worked just as good as a new one. The brace did not come with the Velcro strap that is standard equipment but I had an extra one from another brace because they include two straps with a new brace.

There was one final part that needed to be installed in the lower receiver. This was the magazine adapter block. I had two choices. I had the Pro-Mag plastic block that I originally bought for the project and I had the surplus aluminum block from the PSA kit. While either would work I chose the PSA block. Because it was part of the cost of the carbine parts kit, it was basically a free part for this project. It had a better-shaped feed ramp plus I preferred the aluminum construction to plastic. Many builders of 9mm ARs tell people they need to use one of the pricey adapter blocks that can run as high as $200. I, on the other hand, researched the subject by reading 9mm AR discussion forums and found that actual users said the plastic Pro-Mag block ($35--$45) worked as well as the expensive ones. For those who prefer metal blocks I found that the PSA block ($99) was well reviewed. Readers can use which ever they prefer and can afford but I will be using the PSA block on this project and the ProMag block on my next 9mm AR project.

Both the PSA block and the Pro-Mag block slide in from the top of the receiver's magazine well and are retained by the upper receiver when it is closed. My PSA block was very tight fit in the Anderson receiver and I had to sand a little off the front to allow it to fit in the mag well. I actually prefer having to hand-fit parts rather than having parts fit loosely. To allow the adapter block to drop into the magazine well you have to remove the bolt hold open assembly and then re-install it after the block is in place. I forgot this fact otherwise I would have installed the block before I put in the BHO assembly.

It was now time to do some workbench testing of the project. For this testing you will need to buy or make some 9mm dummy rounds. For the novice, dummy rounds are ammunition that does not contain a primer or powder. They are used to check functioning without the chance of a round accidentally firing. You should never use live ammo for workbench testing. Reloaders can make their own or you can buy them from companies like Brownells. I loaded dummy rounds into a magazine and then inserted it into the gun. I then cycled the action. When testing you need to cycle the action quickly to simulate the speed that the parts would reciprocate during firing. Slow cycling can cause problems that would not exist if running at full speed. When I cycled the action I was please to find that the gun chambered and ejected rounds fine. It even worked when I run it slow. Now that I knew the gun would likely work correctly it was time for live fire testing.

For live fire testing I would be using the same ammo that I had used when testing my carbine project. This was Winchester USA 115-grain FMJ, Federal Aluminum case 115-grain FMJ, and Remington UMC 115-grain FMJ ammo. Since this was function testing I did not bother with installing sights, I just wanted to verify that the gun worked before I applied a final finish or installed sights. I loaded up some ammo in a couple clips and walked out into the driveway and let her rip. Readers should know that I live in the country a quarter mile from the nearest road or neighbor. I can literally stand in the front yard and shoot without bothering anyone. This is one of the benefits of living in rural America. For quick function test I typically just step out of the workshop and shoot a few rounds into the ground. Crude, but effective. During testing I found that the case deflector was causing problems by kicking ejected cases back into the action. Once I removed the deflector all rounds chambered, fired, and ejected fine. The only issue I found was the magazines were a little hard to seat when full since the rounds were pushing up hard on the bolt if it was in the forward position. Since the gun had a bolt hold open on last round feature this wasn't a big problem. If the bolt wasn't back when a magazine was inserted I just had to give it a good hard push to get the magazine catch to engage.

Now that I knew the gun was going to work, I needed to decide what sights I would be installing after finish application. My budget was already stretched to the limit so sights needed to be very inexpensive. Fortunately I had just the ticket in my box of surplus optics. A while back a new gun shop opened in a nearby large city and they had some grand opening sales. One of the sale items was BSA 30mm red dot sights for $19.99. This economy grade sight would be perfect for my budget-stressed project. For those readers who ask where they can get sights cheap I say one thing, CDNN Sports. While this particular sight is slightly higher priced than my sale cost, CDNN does offer this and many other inexpensive optical sights for less than $40. I personally have also bought these type of inexpensive red dot sights used at flea markets and gun shows for as little as $15 so if you look hard you should have no trouble getting inexpensive sights for your project. To raise the red dot to a comfortable height I installed an inexpensive riser that I bought from Cheaper than Dirt for only $ 10.

Because the gun had been built with odd colored parts or parts with no finish I needed to apply a good finish. Some builders take the extremely budget friendly method and just squirt their projects with a can of spray paint. If you use the right paint, this can actually work well. The AR-15 and AK-47 Internet builder's forums are full of reports on decent improvised gun finishes. Because Lauer Custom Weaponry is a big sponsor of my gunsmithing article projects the choice of finish was pretty easy. LCW DuraCoat is an excellent gun finish that can be easily applied by the hobbyist gunsmith. For those wanting an in-depth explanation of the application process, I have covered it in past Firearms News, formerly Shotgun News, articles. The Shotgun News special publication "Shotgun News Gunsmithing Projects" is a 400-plus page book on gunsmithing projects that can be purchased through the store section of the Firearms News website ( In this publication I cover the application of many of the most popular gun finishes such as hot bluing, Parkerizing, GunKote, and DuraCoat. If you have ever considered doing your own gun finishing this book will help you along quite well.

I had a lot of left over and small quantities of DuraCoat from past projects. Rather than using a cataloged color of DuraCoat I mixed several of my left over colors together for a cheap yet high quality finish. For the majority of the gun this color would be a very dark blue. To make it interesting I decided to add some red high lights. The red color was a standard DuraCoat color called "Furious Mike". This is a dark red color that is taking a jab at former anti-gun NYC mayor Mike Bloomberg. Bloomberg made a big stink about guns being painted in DuraCoat colors other than typical black so LCW owner Steve Lauer decided to poke the bear with a big sharp stick just to annoy him for complaining about DuraCoat coloring on guns.

After my sprayed-on DuraCoat cured, I assembled my project for the last time. The budget priced project looked and worked just as good as any expensive factory-made 9mm AR-15. The cost savings from improvising parts and making some of my own parts was substantial. The bare gun without sights came in at $356 total. However, because I did not use the $35 Pro-Mag adapter block and used the surplus PSA magazine block I could deduct the $35 I spent on the Pro-Mag block. This dropped my cost down to $321. By utilizing self-made parts, by finding bargain priced parts and doing the work myself I built a 9mm AR-15 for only about $325, this is a real bargain price for a good 9mm AR-15. If readers could search out some better part prices than me they might be able to cut the cost to under $300. The cost for my bargain basement 9mm AR pistol was less than half the cost of my 9MM AR-15 carbine. While your actual project cost may vary from mine, this is a perfect example how hobby gunsmithing can reduce your cost. I know workshop tools are expensive but those tools are quickly paid for in cost savings when you use them to build budget priced projects. I have thousands of dollars' worth of tools in my work shop but those tools have allowed me to put many more thousands of dollars' worth of quality self-made guns into my collection at extremely low cost. Hobby gunsmithing can allow you to have a gun collection far beyond your income level. If doing a little work to save big bucks sounds good to you why not give hobby gunsmithing a try.



Palmetto State Armory // 3760 Fernandina Rd., Columbia, SC 29210, 803-724-6950,

Anderson Rifles // 1743 Anderson Blvd., Hebron, KY 41048, 859-689-4085,

Brownells // 200 S. Front St., Montezuma, IA 50171,800-741-0025,

CDNN Sports // P. O. Box 6514, Abilene, TX 79608, 800-588-9500,

Slide Fire Solutions // P. O. Box 143, Moran, TX 76464, 325-945-3800,

J+T Distributing / Double Star // P. O. Box 430, Winchester, KY 40392, 888-736-7725,

JSE Surplus // Lauer Custom Weaponry // 3601 129th St., Chippewa Falls, Wl 54729, 800-830-6677,

Copes Distributing //
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Author:Matthews, Steven
Publication:Firearms News
Date:Feb 20, 2016
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