What You Need To Make Your Own AR-15

Many AR shooters are taking a do-it-yourself approach on gun builds. Here’s how to stock up for the growing trend.
What You Need To Make Your Own AR-15

The AR-15, the platform central to the tactical revolution, has long been renowned for its modular construction that allows it to be quickly and easily adapted for a virtually limitless number of roles. By swapping out components, an AR owner can change the look, function and even caliber of the gun. The Mil-Spec design lends itself to nonstop upgrades and tinkering by gun owners, and the sheer volume of parts and accessories means that no one will ever even come close to exhausting the possibilities.

Those same design aspects, however, mean that it’s not all that difficult to build a gun from the ground up. Rather than taking a stock gun and modifying it with a few replacement parts and accessories, gun owners have the option of buying a whole gun’s worth of parts and assembling a custom AR from scratch. Theoretically, all AR components are designed to the same standard and should work together. Just as techies used to buy personal computer components out of mail-order catalogs to be able to build the exact machine they wanted for a price they could afford, gunnies now have the option to create their perfect gun out of the box by skipping the “box.”

In addition to building guns from individual parts, new technology is changing the definition of what “do it yourself” and “customized” can mean. Specifically, 3-D printing is an emerging new technology that makes it possible for gun builders to get exactly what they want while bypassing gun manufacturers completely. Meanwhile, overly restrictive gun laws and the eroding concept of personal privacy are driving some to skirt regulations and put together guns that are legally off the books and might not be available locally in any event.

Like the hot rod car culture of the past, the do-it-yourself approach allows a shooter to build a quality gun out of a collection of standard parts. It can deliver a good gun to your customer that costs less than one on the rack, or builders can put together a high-performance gun for the price of an entry-level gun. The shooter invests his or her time to make up the difference and probably has a little bit of fun during the process and a feeling of satisfaction when the project is complete. As AR owners become increasingly savvy and the number of DIY options continues to grow, this practice is becoming more and more common, and shop owners should make sure that they are prepared to sell more than just complete guns and a few add-ons to customers looking for an AR.

The Sum Of Its Parts

At its heart, the DIY AR approach consists of gathering up components and putting them together to assemble a full gun. The nature of the AR platform allows easy modification, and many owners of modern sporting rifles won’t hesitate to change out handguards, buttstocks or pistol grips. Even more significant changes to the nature of the gun are simple. By popping two retainer pins and putting a new upper receiver on the lower, the shooter can essentially create a completely new rifle. Finally, even more advanced modifications that have often been left to a gunsmith, such as trigger changes or upgrades to the action, are relatively simple on the AR and can usually be performed at home in a short amount of time.

The latest trend, however, is for a complete gun to be built from individual components. Rather than using a stock gun as a starting point, the builder buys a full collection of parts, including receivers, barrels and everything else, to build a one-of-a kind gun that does exactly what the shooter wants. If cost is the main concern, careful shopping can allow a basic but high-quality gun to be built for less than the cost of an off-the-shelf rifle. Though AR builders have always been around, the practice really took off when gun prices went through the roof during the run-up to the 2008 presidential election and worry about stricter gun control — especially talk of a new and permanent Assault Weapons Ban — sent buyers flocking to the tactical shelves at the local gun store and created massive back-orders and long wait lists. Some buyers bought up lower receivers as insurance that they’d be able to get (or sell) a gun if they were banned, and others simply didn’t want to wait until manufacturers caught up with the huge demand for full guns.

The lower receiver, of course, is the registered firearm component of an AR-style rifle. It has the serial number and is the regulated component. Buyers are often amused when they buy a lower and the seller is required to put a lock on the bare receiver. The lower is the basic foundation of an AR project, the hub that everything else plugs into. Once a gun builder has a lower receiver, the rest of the parts are unregulated and can be purchased with relative ease wherever they can be found.

A new product that has garnered a lot of attention is the Omni Hybrid Multi-Cal Lower Receiver offered by American Tactical Imports (www.americantactical.us). It is a polymer unit built over a metal insert that provides strength at critical points. It combines the weight and cost savings of polymer with the strength and durability of metal. Metal-on-metal contact with both the buffer tube and the rear takedown pin ensure durability and consistent firing. It also features an interlocking hammer and trigger pin retention system that prevents movement from the hammer and trigger pin during firing. An oversized enhanced trigger guard and beveled magazine well round out the Omni Hybrid.

Once a stripped lower receiver is in hand, the gun owner will need to get the guts installed. This can be done part by part, but there are plenty of complete parts kits available that contain everything needed to finish out a lower. A great example is the AR-15 Lower Receiver Parts Kit from Rock River Arms (www.rockriverarms.com). It contains all of the internal parts an AR builder needs — plus the pistol grip and trigger guard — for about $70. An advantage of a unified set of components like the kits from Rock River Arms is that the parts are designed to work together to help ensure proper fit and smooth operation. Though Mil-Spec parts should be interchangeable, the reality of manufacturing and varying levels of quality control mean that two parts built at opposite ends of the design threshold might not operate as well as they should when put together.

Buttstock kits for both full rifle stocks and carbine-style stocks are also available and usually include buffer, tube, spring and all the required plates and rings in addition to the stock itself. This has the added advantage of ensuring that the different military and commercial tube dimensions don’t create a mismatch.

Upper receiver assemblies can be built from scratch, part by part, or the builder can purchase a complete upper assembly and simply pop it on. As is the case with ARs bought whole, the ease of mixing and matching upper receivers with a lower mean that barrels and calibers can be swapped out at will. A quick 3-gun platform can be adapted to long-range hunting or rimfire plinking in moments. The Plinker Arms standard .22 conversion upper receiver is a perfect example of a unit that could be used in an initial build or as an added option down the road (www.plinkertactical.com).

Another advantage of building your own AR is that upgraded parts can easily be incorporated into the build from square one. Components such as a Timney Skeletonized single-stage trigger or Magpul’s Batter Assist Device (BAD) Lever — an innovative device which extends a paddle to the right side of the AR allowing the right-hand trigger finger to operate the bolt stop — can be added without having to remove standard parts (www.timney.com; www.magpul.com).

Let’s Party – The 80-Percent Solution

As noted, the lower receiver is the component that is legally considered to be the firearm. Under federal law, the commercial sale of a lower receiver, whether or not the rest of the gun is attached, requires a dealer with a Federal Firearms License, a Form 4473 for a transfer and its associated fee, and the background check. The serial number is recorded, and though gun owners are constantly assured that nothing untoward will ever be done with those records, many are skeptical that the government and all of the individuals in the government can be trusted with so much information about who owns which guns.

Additionally, though the Federal AWB has faded into the sunset, there are many states with various levels of restriction on the purchase or possession of modern sporting rifles. California, Massachusetts, New Jersey, New York and most recently Connecticut have especially harsh controls on ARs and similar guns, and residents of those states have very limited options for keeping and bearing modern sporting rifles. Connecticut’s recent increases in gun control, ramped up in response to the Sandy Hook shootings, have become an example of how skeptical Americans are to firearms control and registration. Some reports indicate that only a small percentage of those who own ARs or standard AR magazines actually registered their firearms and mags, turned them over to state officials, or removed them from the state.

The 80-percent lower is one solution to the restrictions on so-called “assault weapons.” An 80-percent lower is a partially complete AR-15 lower receiver. The last 20 percent or so of the work requires special tools and skills to complete, which meets legal requirements to be considered a non-firearm. Basically, from a legal standpoint, an 80-percent lower is merely a hunk of metal. It’s often referred to as a “paper weight.”

Local laws vary, but generally, there isn’t a restriction on someone making their own firearms for their own personal use. A self-built gun does not have to have a serial number and the government doesn’t have to even know that it exists. Restrictions on what types of firearms may be owned still apply, and laws covering the usage of firearms apply to self-built guns. But the fact that shooters can build an off-the-books gun has prompted huge growth in the 80-percent lower movement.

A basic requirement of a self-built gun is that the work needs to be performed by the gun owner — it can’t be done for the gun owner by someone else, not even as a gift or to “help.” Once the self-built gun is complete, it cannot be sold or transferred to someone else, as the manufacturer is not allowed to build his or her own gun with the intention of transferring it to another party and thereby nullify the “self-built” aspect of the project. Down the road, it may be possible to transfer the “used” gun to someone else, but that isn’t the point of building a gun in this manner.


Whether a gun builder is taking the 80-percent lower approach or not, there are a number of specialized tools that will make a DIY AR project much easier and help deliver better results. While a standard set of gunsmithing tools — such as jeweler’s hammers, punches and armorer’s tools — will always come in handy, there are a number of gadgets that retailers should keep on hand designed specifically for use in AR builds that will greatly ease the process and deliver outstanding results.

If the upper receiver assembly is being put together from scratch, or if changes to a gas block or standard front sight post are called for, the AR-15 Front Sight Bench Block from Brownells can be invaluable. It gives fitted support for installing or removing the front sight assembly. It’s clearly marked on both sides for driving the mounting pins in or out of the sight and accommodates the sling swivel plus includes provisions for removing the gas tube roll pin.

Another tool from Brownells, the CAR-15/M4 Buttstock Wrench, has four teeth that ensure a solid lock on four notches of an M4-type receiver extension nut for easy removal and installation of collapsible carbine buttstocks. It also serves as a fixed stock extension remover (www.brownells.com).

Lastly, most AR builders warn that one of the peskiest parts to keep track of is the pivot pin detent and spring. Putting this into the lower can be akin to brain surgery. Wheeler Engineering offers a detent tool that allows the builder to secure the pin and spring while sliding the pivot pin into place. The tool also helps install the roll pin (www.battenfeldtechnologies.com).


Though there are more ARs available in more configurations and at more price points than ever before, the do-it-yourself approach will continue to grow in the years ahead. Whether used as a way to build the perfect dream rifle, as a chance to save a little money, to avoid inclusion on government lists, or simply as a fun way to tinker, self-built ARs fill a number of niches, and evolving technology is only going to increase the number of options available.

Political efforts to curb “ghost guns” that aren’t catalogued by government agencies or that use 3-D-printed non-metal components to evade traditional detection methods will pass in some places and fail in others, but the same line of thinking that put hot rods on the road and overclocked homebuilt computers in the living room will keep putting home-built ARs in gun cabinets across America.

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