The AR Build
December 30, 2010
How to select the right components for your first DIY AR-15.
The popular AR-15 platform is available in an almost bewildering array of configurations and calibers--from a variety of makers at prices that range from low end to high. So with this kind of choice in off-the-shelf rifles, why would anyone want to build one from scratch? Having built a few in places as varied as a nicely equipped shop to a bunk in Iraq, my answer is simply, Why not?
Actually, with one exception (a Les Baer NRA Match rifle) all my favorite ARs were built from parts at a friend's shop. The most obvious advantage to building your own is, of course, you can get exactly the features you desire. Caliber, barrel weight, length and twist, handguard style, trigger, pistol grip, stock and sights can all be selected from a variety of manufacturers and combined.
Then there's cost. It's usually less expensive to build a rifle exactly the way you'd like it, compared to buying off the shelf. And let's not forget the pride factor either. There's something special about building an accurate and reliable rifle. It instills a pride of ownership that you don't get from simply buying a factory rifle.
Unlike crafting a custom Mauser hunting rifle, you don't need to be a skilled gunsmith to assemble a good AR. If you have a modicum of mechanical aptitude and mix it with thoroughness and some patience, you can do it.
The job requires a few specialized tools such as a barrel wrench and headspace gauges, but they are readily available and inexpensive. Other items, such as a block to hold your receiver in a vise, are handy but not mandatory.
The most important, and perhaps the most overwhelming, part of building an AR is choosing what parts to utilize because there are just so many available. That said, there are some basic truths and advice that will help a novice select the correct parts to build an accurate and reliable rifle.
Before you even begin to select parts, you first need to decide on exactly what type of rifle you want. Do you want a rifle for personal protection, a match rifle for NRA highpower or 3-gun, a varmint rifle, big game rifle, long-range rig or a military clone?
At the same time, of course, you need to choose your caliber. I suggest doing your first build with the .223 Remington/5.56 NATO chambering, unless you have your heart set on a big-game or long-range gun.
Once you know what you want to build, you'll need a barrel wrench and a few other readily available tools.
With that out of the way, it's time to get to work. I think the best place to start is the upper receiver. You have three basic receiver types to choose from: the old-school M16A1, the M16A2 and the current flattop. I like the flattop as it's the most versatile. You can easily install iron sights, a detachable carrying handle or optics on a flattop.
For a basic lightweight carbine intended for use with iron sights, I suggest an M16A1 upper. Its simple yet effective sights lack the large adjustment knobs of the A2, which are easy to turn by accident. For an NRA highpower match rifle, though, the A2 upper is the way to go.
When selecting an upper, I recommend staying with one of the top-tier manufacturers. Although Colt is nice, its units are expensive. Consider a Lewis Machine & Tool (LewisMa chine.net), Stag Arms (StagArms.com), Rock River (RockRiverArms.com) or Bushmaster (bushmaster.com) instead.
If you want to take a step up, look at a LaRue Stealth (LaRueTactical.com) or a Les Baer (LesBaer.com). I've built most of my ARs on Rock River uppers.
When choosing AR parts, you have to keep in mind the unfortunate fact that some companies do sell substandard parts. So while there are bargains to be had, it does not pay to buy the cheapest parts you can find.
One place you definitely don't want to go cheap is the bolt carrier assembly. You want a quality bolt and carrier with a properly staked gas key. One I recommend is Bravo Company's BCM bolt carrier group (Bra voCompanyusa.com). It features a Parkerized exterior, a chrome-lined interior and a mil-spec, chrome-lined gas key that's properly staked and secured to the carrier via Grade 8 fasteners Plus it's Magnetic Particle Inspected. Price is $130.
If you want a step up, consider a Young Manufacturing (NewRiv erArms.com) or Les Baer National Match bolt carrier assembly.
No matter what caliber you choose, you'll want a good quality bolt carrier with a properly staked gas key and a good bolt assembly.
The barrel is perhaps the most important aspect of the rifle. It will dictate not only how the rifle shoots but also how it handles and balances. There are three basic barrel types: standard chrome moly; chrome moly with a chrome-lined bore and chamber; and stainless steel.
Chrome moly is the standard for rifle barrels and is fine for recreational use and hunting. Stainless steel is more resistant to corrosion, has a longer life and is preferred for precision and match rifles.
Chrome-lined barrels are plated with metallic chromium to make them more resistant to heat, chemicals, erosion and abrasion than bare chrome moly or stainless steel. Chrome-lined barrels also last much longer than unlined barrels and are easier to clean.
The downside is it's not possible to do a perfectly uniform job of chrome plating. So your average chrome-lined barrel will not be as accurate as a good stainless barrel. That said, I have a couple of chrome-lined AR carbine barrels that shoot into an inch or less at 100 yards. I would consider a chrome-lined barrel a must on a self-protection rifle.
If you're building a .223/5.56 rifle, you also need to consider the rifling twist rate. With today's heavier bullets, I suggest a 1:7-inch twist for a general-purpose carbine/rifle. This will allow you to shoot projectiles weighing up to 80 grains. I'm not a fan of 1:9 twist barrels, simply because I think the 1:7 inch twist is more versatile. For a competition rifle I would select
a 1:8 twist.
You also need to carefully consider barrel weight. If you are building a carbine for self-protection, you want a rifle that will be quick-handling, so I highly recommend a lightweight "pencil" barrel or at most a government profile. Just keep in mind when selecting a barrel profile, especially on a carbine, to take into account the weight of the accessories you intend to mount.
On a match rifle or varmint rig, a heavy 20- to 24-inch barrel is more appropriate. And if you're building a precision rig, know that not all "match-grade" barrels are created equal. If you're looking for the utmost in accuracy, stick with a top-tier barrel maker. I've had excellent luck with Les Baer's Benchrest grade barrels, but there are many good barrel makers out there. Just do a little research and choose wisely.
Barrel length and weight will make a huge difference on how a rifle handles, and it's important to consider how many accessories the rifle might wear.
When it comes to muzzle devices, you need to choose whether you need a muzzle brake or a flash suppressor. On a defense rifle I would consider an effective flash suppressor mandatory.
Although there are many types and styles, I recommend considering just three. The first is the plain Jane A2. Although not very sexy, it is inexpensive and fairly effective. If you want to take a step up, consider either Yankee Hill Machine's Phantom (yhm.net) or Smith Enterprise's Vortex (SmithEnterprise.com).
Both of these devices are highly effective and offer better flash suppression than the A2. If you want the bling, go with the Vortex. If you want to save some money, go with the Phantom.
If you are a 3-gun competitor or a varmint hunter, a muzzle brake will be more useful. Two I suggest considering would be JP Enterprises radical-looking Recoil Eliminator (JPrifles.com) and Holland Shooters Supply's Quick Discharge muzzle brake (HollandGuns.com).
Both work extremely well. The Quick Discharge offers a lower profile and is a bit more traditional looking. The Recoil Eliminator features more radical styling.
Gas block choices include a traditional front sight assembly; one with a folding front sight; low-profile units; and models with integral rails. On a carbine for general use, I prefer a traditional front sight assembly. But on a precision rifle that will be used with a magnified optic, I recommend a low-profile unit from LaRue Tactical, Precision Reflex (pri-mounts.com) or Vltor (vltor.com).
My main word of advice when it comes to gas blocks is to use one held on by crosspins on a defense rifle. Set screws can loosen up under prolonged firing. Gas blocks retained by set screws are okay for recreational, hunting and target rifles.
Selecting handguards can be difficult as well because there are so many kinds. On a defense carbine, the standard military handguards are fine because you don't need a free-floated barrel. If you want a bolt-on rail system for adding accessories, there are many good choices. Check out SureFire's unit (surefire.com) or Yankee Hill's two-piece handguards.
If you'd like a railed handguard that free-floats the barrel, consider those from LaRue Tactical, Precision Reflex or Daniel Defense (Daniel Defense.com). Prefer a free-floating handguard but want to have rails only where you need them? Take a look at Viking Tactics' Modular Handguard System (VikingTactics.com)--a lightweight, round handguard that allows you to install different length rail sections where you want them.
Don't want rails? Well, I really like Alexander Arms' lightweight composite free-floating handguards (Al exanderArms.com).
There's a variety of collapsible stocks available. Fortier advises using a mil spec-diameter buffer tube and recommends an H or H2 buffer.
Once you have everything picked out for the upper, it's time to select parts for the lower receiver. This is easy. Start by selecting a good quality lower receiver, using the same criteria I outlined for the upper.
If you purchase a stripped lower, you can choose from either stock military-type fire-control parts or a match trigger. I do not recommend putting a match trigger in a self-protection rifle. Match triggers have extra parts that can cause problems under hard use and abuse, so stick with good quality military-type parts.
If you would like a better trigger pull, any good gunsmith should be able to take quality fire control parts and tune them to provide a crisp 4.5- to five-pound pull without comprising reliability.
For a match rifle or varmint rifle, go with the best match trigger you can afford. I highly recommend both Jewell and Geissele (geissele.com).
When it comes to buffer tubes on carbines, keep in mind there is a mil-spec diameter and a commercial diameter. I recommend a mil-spec buffer tube. Carbine buffers are available in different weights:
'¢ standard CAR, 3.0 ounces
'¢ H, 3.8 ounces
'¢ H2, 4.6 ounces
'¢ H3, 5.4 ounces
'¢ 9mm, 5.5 ounces
A heavier-than-standard buffer is useful for reducing perceived recoil and making the rifle feel smoother when shooting. This is especially useful on carbines with the short CAR-length gas system, but mid-length guns will also benefit from a heavier buffer.I suggest going with an H or H2. Although it's fairly expensive, I have also had excellent results using MGI's Rate Reducing Buffer (MGImilitary.com). Just remember that you can tune how your rifle cycles, and recoils, by changing buffer weights.
When it comes to pistol grips, I prefer Falcon Industries Ergo Grip (ErgoGrips.net) and Magpul's offerings (magpul.com), but an old-school A1 grip works fine.
Muzzle brakes such as Holland Shooters Supply's Quick Discharge reduce recoil, which is important for such tasks as 3-gun competition.
Regarding buttstocks, sometimes simple is better. For a fixed stock, a simple A1 military stock is hard to beat. Shorter than an A2, it fits most people well and is inexpensive. The downside is that it is not as robust as an A2.
If you are building a carbine, you will want to consider offerings from LMT, Vltor and Magpul. These "high-speed" stocks come with a higher price tag. Although not as sexy, a standard mil-spec M4 stock works fine.
For a precision rifle you'll use with a high-magnification optic, consider MagPul's PRS. It has an adjustable cheekpiece and is adjustable for length of pull.
That about does it. Keep in mind that you don't have to spend a ton of money on fancy components, and in fact you can build an accurate and reliable rifle using an inexpensive receiver such as Model 1 Sales' upper (Model1Sales.com). Just make sure the bolt carrier's gas key is properly staked and perhaps upgrade the extractor spring. Mount this onto a decent lower with good fire-control parts, buffer and spring, and you should be good to go.
By carefully selecting your parts and being methodical in your assembly you should have no problem building your first AR. When looking for quality AR parts and tools, I highly recommend Brownells. If you're looking for information on parts, accessories, tools or have a question during assembly, the web board AR15.com offers a wealth of knowledge.
Once completed, don't forget to introduce a friend to the fun of shooting your new black rifle.