An Amateur’s Look at an AR Build Course

Recently my local gun shop in Bloomington, IN allowed me to sit in on one of the shop’s new AR build courses being offered. I didn’t build a rifle there myself, just simply watched the course intently and took a large number of notes and photographs of what was going on. Because I wasn’t an actual student involved in the course, this won’t be an article detailing the intricacies of putting together an AR15 but is simply more a reflective perspective of what I learned. If you are interested in a rather in-depth critique of putting together an AR15, take a look at Patrick R’s writings. In addition, I know I’ll get some particular facts here wrong, so please take this as an outsider’s perspective on a very detailed aspect of the AR15, instead of a true testimony.

The history of amateur and limited home gunsmithing did not start with the mass popularity of the AR15. We certainly have accounts of American frontiersmen completing limited DIY work on their rifles from the 1800s and 1700s. Mending stocks, replacing worn parts, maybe even changing out a barrel. Our counterparts in Europe probably experienced a similar amateur experience but I don’t believe firearm ownership in Europe has ever reached the historical levels it has been in the United States (apart from Switzerland). This tradition continued into the 20th Century as we have much evidence of sportier Mausers, Springfields, and various other military small arms. But with the adoption of the M16 by the U.S. Military, and subsequent popularization in the civilian sector in the 1990s and explosion post-OIF/OEF, putting together an extremely accurate or reliable rifle has literally never been easier in the history of amateur workmanship. As a mentor of mine once mentioned, “ARs are essentially like LEGOs, snapping everything together”. To be honest, he wasn’t far off.

Note that my usage of the word amateur gunsmithing in this context is to differentiate between an actually certified gunsmith that works professionally and a gun owner that is very involved with their personal firearms.

The AR Builders Course was hosted by American Arms, a gun store in Bloomington, Indiana. The owner, Matthew Barthold, was a prior shooter on the Marine Corps Shooting Team. Matthew was involved in numerous instructing courses after his departure from the Marine Corps, then opening his own shop in Bloomington where most of his business is putting together AR15s. His partner in teaching the course was Nicholas Gillespie, a former small arms repair technician at Naval Surface Warfare Center Crane in nearby Crane, Indiana. Both of the two gentlemen had many years of experience between them in building and repairing AR15s, in a civilian and military capacity.

First off, I didn’t realize how many specialized armorers toolkits existed for the AR15 platform. Given the platform’s popularity, this should have been a given, but I was still caught off guard. A lot of the kits came from Brownell’s but this was because the shop mass-ordered the tools from the company. Numerous other industry names make and market similar or better tools. Within these tool kits were upper receiver clamp bits that allow the receiver to be placed in a vice and tightened down without actually bending or harming the upper. Then there was the punch kit that is outfitted specifically for the AR15’s different sizes of pins and other such indents. As Patrick mentioned in his article these are important for punching out parts while not flattening or otherwise damaging them. Then there was the hammer with the nylon portion on one side, and brass portion on the other, allowing a user to hit different parts by either a softer blow on the nylon side, or a harder blow on the brass.

Probably the hardest portion of putting together an AR is the barrel and gas system. Granted, it is much easier to attach an AR barrel to an upper receiver than it is to press a Kalashnikov barrel into a trunnion. But even so, this is probably the largest reason why we are seeing constant improvements in barrel assemblies and even quick change barrels that can maintain a zero, even between calibers. Installing the barrel nut over a traditional barrel required the barrel installation tool, that when coupled with a torque wrench, allows an extremely tight fit between the barrel, barrel nut, and the upper receiver.

A significant portion of the class was spent on working with the handguard assemblies, most of the students using the original and standard Delta assemblies that the original M16A1-M16A4 are known for. These contraptions are much more of a problem installing than I thought they would be, involving some very tight coordination between the wide spring and the ring itself. Again, just like with the barrel nut assembly, one can easily see why a complex mechanism like this is trying to be ushered away by the industry because of just how complex and difficult they can be for people at home to work with.

The next item was the gas tube. From a shooters perspective never really dealing with a direct impingement gas tube, it never really comes into play unless of course, it becomes damaged. But actually watching the instruction and then installation of the gas tube and gas block made me have a new respect for anyone efficient enough to do these on their own multiple times over. From the barrel nut earlier being properly aligned with the tube, to measuring and making sure the tube was at the correct distance to the gas port, then finally pinning the gas tube into the block securing the block in place on the barrel. And I thought installing the front take-down pins was difficult!

Matt, the instructor of the course, was sure to point out the differences between a Mil-Spec and a commercial buffer tube along with their accompanying butt stocks.

The rest of the class covered installation of various other parts but these are relatively minor compared to working with the gas system and barrel assembly. As I’ve heard one Youtuber mention, the entire AR platform is “relatively forgiving” if you are gentle enough and have sort of an idea about what you are doing. Fitting in pins, springs, and other minor devices aren’t that difficult when you put your mind to it.

Nick explains the necessary barrel nut torque-

I hope that this is the beginning of some very in-depth knowledge about the intricacies of the AR15, which is certainly one of America’s most popular rifles in recent times.


Infantry Marine, based in the Midwest. Specifically interested in small arms history, development, and usage within the MENA region and Central Asia. To that end, I run Silah Report, a website dedicated to analyzing small arms history and news out of MENA and Central Asia.

Please feel free to get in touch with me about something I can add to a post, an error I’ve made, or if you just want to talk guns. I can be reached at


  • TheNotoriousIUD

    Wish I had a box of shiny new parts and nothing to do on a Sunday afternoon.

    • PK

      Here I was, griping that I had to build two “loaner” rifles over my lunch break due to lack of time away from my desk… perspective helps. However unintentional, thanks for the written dope slap.

      Also, now seems to be a great time to get an AR or five together. Kit prices and lowers abound, and prices are very reasonable. Total cost each on the rifles I built ended up being just under $400 with sights and a pair of mags.

      • TheNotoriousIUD

        I find building rifles relaxing.

        Sometimes ill take one out of the safe and break it down and give it a good cleaning and lube while im watching TV even if it doesnt need it.
        But I might also find it annoying to be rushed on my lunch break.

        • PK

          “But I might also find it annoying to be rushed on my lunch break.”

          That’s the problem, exactly! Normally, I enjoy building even very basic ARs. Doing it while trying to work without my usual tools and fast enough to leave time to eat, however…

      • Swarf

        I’m thinking about getting a bare bones rifle just because of that price.

        I have no real passion for the AR platform (old military surplus and lever actions are more interesting to me), but for $400, there’s not much excuse to not have one.

        What do you recommend to put together something like you mentioned in your post?

        • PK

          Honestly, it depends on your brand preferences (if any), but if you’re totally open to whatever, so long as it works… Palmetto State Armory runs specials regularly, where you can get a “bare bones” kit for about $350 with free shipping. That, plus any inexpensive lower bought locally, and there you have it.

          I managed to snag a number of kits which were on super sale, and when buying sights there was a package deal which included 10 PMags. I’ve built more than a few of the simple, basic range rifles!

          Local AR lowers are an option for me, but if they’re not available at a decent price ($50 or less for Anderson, for example) then you can look around online. Many retailers seem to be clearing out the excess stock now that demand has plummeted, and this stretch of time will very likely be looked back upon fondly as the “good old days” of low cost ARs, one day.

          Happy building!

          • Swarf

            Thank for the advice, I appreciate it.

          • PK

            You’re quite welcome! You’ll find that the cost, ease of assembly, and overall ease of use will explain the current popularity. ARs may be boring, but they simple work. The modern take on everyone owning a single shot shotgun, really!

  • Steven M Case

    People actually pay for these “classes” ?

    • None

      They definitely do. LaRue charges $650 for theirs. I’m a certified Youtube armorer and proud of it.

      • neckbone

        Larue could charge guys $5000 to give him a bj and certain guys would line up and wait. It’s a cult like following. I do prefer the mounts though they make.

      • Wow!

        I have had “professional” training and to be honest, the internet has resources that are a lot better because it is a compilation of people doing trial and error and finding the best technique rather than “do it because it is ‘mil spec'”. Well sorry, I’m not in the military and none of the firearms I make will ever truly be “mil spec”. Mind as well do it the way that best fits my needs.

    • Matthew F Barthold

      Being the Owner of American Arms and having multiple people a week come in wanting help on various firearm. Classes get you the on hands time with questions being able to be asked and answered. Also being able to have the possible firearms there that you would like to utilize.

      As for bringing firearms in for repair. We could either charge them for the time it would take to work on there firearm and not have that firearm get any damage on it from US having the experience or we could charge them even more to have them watch because now it will take us even more time to get the job done because of questions being asked during the job.

      Or they can watch youtube videos and try it themselves. (Which on occasion I have had to do myself) We have seen in over 5 years hundreds of firearms brought in because people thought they could do it themselves and I applaud them for it. On the other hand try not to get to deep into something especially if you don’t have the proper tools. You should watch the videos first before trying to disassembly to see if it is something you really can tackle on your self. Not start doing it and realize parts start falling out and during that time someone in the video says ” oh and by the way you should have this tool to help you put this part that fell out back in”. That is the time you say crap what have I gotten my self into!!

      Not only that, there are time you have to really use some force with the proper tools and the sound alone scares people and they they think your damaging their firearm. This is annoying when they start to complain about what your doing to their firearm! We have Thousands of dollars in tools to help get these firearms apart and together proper and even still there has been time something has still broken. The good thing on the customers part is that we pay for and not the customer.

  • Ark

    I didn’t know Miles was in B-town. Must be just down the road from me.

    AA is pretty neat, but Traildust across the road is my favorite firearms-related store in town. Only place I can buy 8mm Mauser without going online.

    • Stephen Baker

      Hey, another Bloomingtonian here. I didn’t know there where this many shooters in these parts!

      • Ark

        Wow. Go figure.

  • Sledgecrowbar

    My introduction to building an AR was the Brownells video series, free on their website. One of the better sets of instructions for anything I’ve ever seen. I like the way they tighten the barrel nut, you have to buy their barrel extension “socket” but it has become one of my favorite tools and having a 1/2″ square drive means you can torque it right on the axis, not that this is difficult when you can just turn a torque wrench 90 degrees from the barrel nut wrench and accomplish the same thing but I like it. I figured the barrel extension pin might over-stress the slot in the upper receiver, and I was right once due to over-torque-ing but otherwise it’s not a problem. Outside of that, the video series is really good for showing the complete process start to finish.

  • Marcus D.

    I built my first AR with a polymer 80% lower, an electric hand drill, and tools I already had, no special armorer’s kit. I had a link to a great site that has step by step instructions with photos that was perfect. The only thing I had to go to the gun store to do was to torque the barrel nut because I could not get the Hogue special wrench that goes with its free float tubes to fit around the nut as it was supposed to. And everything worked just the way it was supposed to.

  • Bub

    I took one of these type classes a few years back and found it to be a great experience. Springs and detents were flying everywhere by 10:00am the first day. It helped me really appreciate the workings of the AR. The really are incredible designs. May sound crazy to some, but I take classes like this for fun and recreation as much as anything.

  • jerry young

    I have built a couple of AR’s and never took a course, being the type that if something can be done then I can do it too, I researched what I needed to know and of course working in an armory for the last year I spent in the Army helped, I bought kits and a part here a part there, a few needed tools and went to work, I have to say it was easy and fun to build them what I didn’t know was on the internet all I had to do was look, it brought back memories of the days spent working on guns, right now I’m collecting up the parts for an M16A1 replica of course it will be semi auto not wanting to get into all the expense and red tape of full auto guns, I do want to use authentic M16 parts as much as I can so I’m looking for places to buy good used parts.

  • Trotro

    I’ve used pistols for numerous years but am pretty noob to the AR platform. Took a class a few months ago for 40 bucks and spent 3 hours where me and 1 other broke down a basic Anderson rifle and put it back together. I though it was money well spent just in getting to know what all the little parts were for. But hot damn was there a lot of little springs and detents!

  • Wow!

    People get scared building AKs because you have to make “permanent” changes such as drilling or welding (I do weld builds because they are super simple) but really an AK is as easy as an AR. I mean, it really is hard to screw up an AK build if you build in the right order. There is this myth that America’s tight tolerances can’t adapt to Russian loose tolerances which makes it hard to build an AK but that is BS. The reason some American AK’s fail is because they use American parts that are cast rather than milled from stock (because a private company does not have the government resources to make an entire factory dedicated to producing trunnions and bolts). It has nothing to do with tolerances. Even with a mix matched parts kit, you can produce a very tightly running firearm if you build in the proper order as each part indexes on the other (just like every other firearm in existence).