I get the question about building AR’s often. Whether it be on Instagram, in person, at work, on Facebook, from complete strangers, or people I’ve known forever the question pops up a lot. Actually, it comes a lot from people who find my clone rifle stuff. People want to build cool rifles that function well.
What people don’t realize is that building an AR is like opening the biggest can of worms that there is. They soon realize that there are a million options out there for parts and so many directions to take their build that they don’t know which way to go. To compound the issues, often times budgets are limited and no one wants to buy junk. The ultimate goal is a reliable rifle that does what you ask of it.
Once you venture down this road, often times you get a feel for what works, what you need, and what you like. If its your first build, then you might not be going into it with that same “feel.” I’m hoping that with this series of posts I can help make it easier to build rifles for people who are setting out on this journey. After all, that’s exactly what it is, a journey. If you’re anything like me, you may spend years tuning the rifle to yourself and getting to know your rifle very intimately. Its a very rewarding experience.
Getting Started… Tools…
The AR-15 is truly the Lego gun of the gun world. Despite this fact, it’s not all plug and play. Not all the parts just drop right in tool free. You can get by with very few tools, but often times it is not a good idea. So what tools do you need? Well, lets talk about that.
I do hate to break it to you, but you might want to up your budget to include some tools if this is your first build. Some tools you’ll more than likely have and others you wont. First and fore most, you are going to need a good set of punches. To accompany those you will also need a good hammer. Something with both brass and nylon ends is nice. You’re not going to want to use a framing hammer. The risk of dinging or damaging your receivers is far too great. A decent starter set would be something like Wheeler’s Punch Set. Its not great, but it will get you moving cheaply. Expect to bend and mushroom them if you abuse them though. Its is, after all, a starter set.
You will get very familiar with roll pins. It almost feels like everything takes a roll pin. The hardest thing when dealing with roll pins is starting them. You may smack your fingers with your hammer more times than you’d like. To prevent this you can also get a set of roll pin punches to hold the roll pins and help you start them. This is, however, totally optional. Another good option to help start those pesky roll pins is a set of needle nosed pliers. With that said, a basic set of hand tools does come in handy period.
One other thing that people don’t often think of when dealing with roll pins is masking tape. Yep, that old roll of painters tape that you have floating around your junk drawer. How could this possibly help? Well, you can mask off the area around the roll pin to reduce scratches and marks on your receiver. Its cheap insurance to prevent scratches.
You may or may not already have a plethora of screw drivers. I know I do. While you might not use them much on the AR itself, you will still need them. Typically your grip screw will either be an Allen head or a flat head. Thus its always good to have options. One thing I’ve found is that it is also good to have long options. Especially when working on various platforms, not just AR-15’s. I’ve found myself in need of longer Allen bits when working on my Remington 700 and various other bolt guns. Especially when mounting actions in stocks or chassis.
Being as though you will more than likely be installing parts from various manufacturers, you will probably need a vast array of bits. While I suggest a good set of screw drivers, a set of hex drivers/Allen wrenches, and a screw driver that will allow you to swap various bits is a must. Don’t think that you can get a couple of screw drivers, a set of bits, and you’ll be set for your gun smithing career.
What do I suggest? If you’re on an extreme budget, then at the minimum get yourself something like the Wheeler Gunsmithing Screw Driver set. I’d also recommend an extensive set of torx bits. You will 100% also need a good set of both metric and SAE Allen wrenches. That will get you a long way. Long T-handle torx and allen sets are nice to have on hand as well.
Torque matters. Yup, there are various parts of the AR-15 that actually have torque specs. In the bolt gun world things like the torque on your actions screws can actually affect your accuracy. With that said, I’ve seen various people claiming that certain amounts of torque on your barrel nut will net you more accuracy. I have not really put this to the test though. All of that said, I’ve found that I build AR’s that shoot just fine when not torqued to any of the various magic numbers. So don’t worry too much about them unless you’re building something for long range work and have the time and patience to experiment. Just get that barrel nut to the recommended torque range.
A good torque wrench is a must. You will need to torque both your Castle nut on the buffer tube and your barrel nut. Your gas key screws also need to be torqued, but you more than likely will not ever need to do this unless installing a new gas key. Most BCG’s will come with the gas key properly installed and staked. Flash hiders should also be torqued to manufacturers recommended specs. On top of that your scope mounts will more than likely also come with manufacturers recommended torque specs.
Another nice to have tool is a Wheeler FAT Wrench. Its like a screw driver, but its a torque wrench. Its easy to use and I often find myself using mine. In fact, I use it a lot. It takes 1/4″ bits, so all those bits for your screw driver will also work here.
Another excellent tool to have are Fix-it Sticks. Bolt gun guys swear by these things. They’re a set of t-handle drivers with torque limiters. The limiters come in many different limits. The best part about these is that they’re compact, light weight, and they can fit easily in your kit for field repairs. If you’re planning on spending time in the back country then you should also look at keeping tools on you to keep your gun running and these should be part of your tool kit.
So we talked about screwing things. Lets talk about gluing things. No, you don’t actually glue anything onto your AR-15. You will loctite screws though. A lot of parts come with manufacturer pre-applied loctite on your screws. Some don’t though. One thing is certain. If you forget loctite, then parts WILL come lose. For example, the Arisaka light mount on my Dissy rattled loose during a class because I forgot to loctite it. It took a special short Allen wrench to tighten and subsequently that gun went down because I didn’t have the wrench on me at the class.
So loctite is important. There are typically 3 types of loctite that I use. All 3 types have different applications. The 3 types are purple loctite (or 222), blue loctite (or 243), and Rocksett. One of your primary goals in building your AR15 should be preserving your threads. You don’t want to strip or damage any threads. This is why I use different kinds of loctite.
On applications where I’m dealing with any aluminum threads, then I tend to gravitate toward Purple loctite. It is designed to work with soft metals like aluminum and brass. You can remove screws treated with it easily, but they wont back out on their own. Blue loctite is reserved for steel on steel action and it is a medium strength thread locker. It is easy to remove screws treated with it by hand (no heat required). Heat is the enemy of most tread lockers. In fact, heat will make it easy to remove screws with most loctite. On applications like muzzle devices loctite is not a good option. This is where I use Rocksett. It keeps your muzzle devices good and planted. It can be a pain in the ass to remove.
Some times loctite isn’t the answer. Like on barrel nuts. You should never use loctite on the threads of your barrel nut. Like, never… The same goes for your castle nut. In fact, the mil spec calls for grease, but not just any grease. Without getting horribly far into the weeds on this topic, I’m just going to say that the most easily acquirable grease that fits the mil spec is Aeroshell 33ms. You get it cheap and by the tube. If you go that route, then you’ll have enough to build about 600 AR’s… That’s what I did and I’m still on my first tube.
It doesn’t moo.
If its not loctited, then it might need to be staked. There are a few parts on the AR-15 that do in fact require staking. Typically you gas key does, but usually your BCG will come with a staked gas key. The other item that needs staking is your castle nut. I’ve seen many methods to staking, but the one I tend to use requires a spring loaded punch. At least on my castle nut. Typically you can get them for dirt cheap at Harbor Freight and they will work just fine for staking a castle nut.
Keep in mind that if you choose not to stake items that should be staked, then you are risking failures and potentially bad ones. I’ve yet to see a failure that resulted in any injuries, but I have seen peoples guns literally start falling apart. As in the castle nut backing off, causing the little nub on the end plate to round off so that it could rotate and lose the rear pivot pin detent and spring. It wasn’t my gun, but I did fix it for the person.
Holding your horses…
See what I did there??? Okay, that was bad… So many times working on your rifles leaves you working in an awkward position. Its hard to hold your rifle in place. Some times you can put your counter top or your receiver at risk as well. This is where receiver blocks come in.
I’ve worked with a number of receiver blocks. Some garbage and some great. Either way, when you’re torquing your barrel nut, this is a tool you will want. I’ll start by saying avoid actual clam shell style upper receiver blocks like the plague. I’ve ruined many. They tend to crack, split, and twist apart with use.
The other down side to the clam shell style blocks is that they still allow the receiver to twist. One thing to worry about is twisting your aluminum upper receiver. It will essentially make your upper into a paper weight.
The right blocks…
There are two style blocks that I recommend. Both of them work off of the same principle. The first being the Magpul Bev Block. It slides inside the bottom of your upper receiver and engages into the lugs of the barrel extension. Those lugs are plenty strong to hit the torque spec of your barrel nut and no twisting force is exerted on your upper. You then pin your upper via the take down pin holes to the block and insert your bolt carrier without the bolt into the back of the receiver. This nets you a rock solid solution for holding your upper.
The next option I recommend is a Giessele Reaction Rod. It operates off of the same principle as the Bev Block. The Reaction Rod engages the barrel extension. The upper is not locked in place though, allowing you to quickly remove it or spin the upper to work on it from a different angle. This is really handy.
One thing to note. All these options including the dreaded clam shell option will require a bench mounted vise to hold them. There are also lower receiver blocks which mount in vises as well to hold your lower receiver in place for things like torquing the castle nut on the buffer tube. Typically they mount to the gun via the mag well. Just make sure that if you use one, its sturdy.
You can use gun vises. While not necessary, you might find them useful for holding your gun while performing certain tasks and doing maintenance. Most of these are table top vises. I’m talking about things like the Tipton vises. I’ve got one, but it doesn’t see much use. Its not a bad tool to have around, especially for working on guns other than AR-15’s, but I’ve found it a bit more limited on the AR-15 front.
One aspect of putting together an upper which some people might find challenging is the gas block. How do you line it up? Do you pin it? Does the barrel need to be dimpled? Do set screws really work? I’ve never had set screws back out or a gas block spin on me, but I’ve also taken this part of the build very seriously. After all, an issue with your gas block will take your gun out of action.
One tool that I have found very useful is the BRD Engineering gas block jigs. If you are installing your own gas block then this is a life saver. Many gas blocks use set screws to lock themselves in place. This doesn’t necessarily prevent them from spinning though. If you dimple your barrel so that your set screws are inset into the barrel, then your gas block will not spin.
The BRD Engineering makes jigs for many different gas blocks. Their jigs self align with the gas port, placing the dimples in the proper place. All you have to do is use the proper size drill bit to dimple your barrel. It makes the process pretty simple. They also make all manner of other jigs and it is well worth checking them out to see if they have a jig for your application. They are spendy, but well worth it.
One other special tool which I some times use is a tool to lap the front of the upper receiver where the barrel extension meets the upper. What does this do? It trues up the receiver face. This is a step that many people take when accurizing their AR-15. Is it necessary? No, but if you’re building something geared toward precision, then it might be worth while.
On the topic of gas blocks, you may choose to run a FSP instead of a low profile gas block. Installing one from scratch on a virgin barrel is not something I recommend people who have little to no experience building AR’s. They are your front sight, so they must be plumb if you want to actually use them. Also, they are not installed with set screws. They use taper pins. Pinning them in place makes them absolutely bomb proof. This also means that you need to drill holes in your FSP and through the bottom of your barrel as well as ream the holes.
If you’re not mechanically incline, then you’re probably thinking that this option is not for you. It can be though. Many manufacturers sell barrels with the FSP pre-pinned in place. This is a great option for most people who want a FSP. Some times the manufacturer will include a barrel nut as well. This is great if you just want to slap the barrel on and use some manner of drop in hand guard.
If you want to run a FSP and a free float hand guard, then you’ll need to pull that FSP off to install the barrel nut and hand guard. This can be a huge pain in the ass. I have a block that the FSP nests inside, holding the barrel and fsp in place. Its reversible so that it can be used to both remove and install the taper pins. The block sits tall enough and has holes so that the taper pins can drop out. I looked on Amazon for the exact block I have, but could not find it. Brownells does have a similar block though.
There are two other important tools required for removing a FSP. A big hammer and a sturdy punch. I took a bigger punch and ground down the tip to fit the tapper pins. Using these tools required less beating on the pins, but they can still be a pain in the ass to get out.
Its always a good idea to have a good set of hand tools around in general. Some times a set of wrenches comes in handy. I will say that channel locks are NEVER the answer though. A set of sockets might also come in handy as well. I don’t find myself using sockets and wrenches often, but occasionally I do.
The one wrench you will use is an armorers wrench. This will have lugs to tighten a castle nut, barrel nut, and perform various other functions on your AR-15. These are a good tool to keep around. I’ve gone through a handful of them and they definitely are not all created equal. In all honesty, I cant even remember all the brands of wrenches I have used (I’ve had many) and which I’ve broken. This is a must have tool.
Some handguards will use a proprietary barrel nut, which will require a proprietary barrel nut wrench. On top of that, some times the wrench has to be ordered separately. So make sure you have it on hand if you need it. They will have a socket to hook your torque wrench to so that you can get your barrel nut in that torque spec range.
That’s a lot of stuff man…
I’ve talked about a lot of tools and there are still more things that are nice to have. This just covers the basics with a little extra thrown in there. You can get by with the minimum, but certain parts of the process might become a bit harder. If you’re using a buddy to hold your upper to the table while you try and torque the barrel nut, then you’re definitely doing it wrong. That’s why its nice to be tooled up. You can do all your own work without risking ruining your expensive parts.
You don’t need every thing I talked about or at least not all at once. Getting away with the bare minimum is possible, but its hard to know what exactly you’ll want or need until after your first build. I hope this gave you a good idea of where to start though. I’m sure that I’ve also missed some minor niceties. If you’ve got any specific tools you keep in your tool box or neat tricks, I’d love to hear them as well. I’m always down to learn new methods to get the job done.
Next up in this series I’ll dive into the AR-15 as a whole and cover the parts needed. Beyond that I’ll start breaking things down and perhaps really get into the weeds. Stay tuned for more.