Best AR-15 Upper and Lower Receivers

The AR-15 platform is by far the most popular rifle in America. Known as America’s rifle, and sometimes as LEGO for grown-ups (due to its modularity, interchangeable parts, and ease of customization), the ArmaLite Rifle has certainly been improved and iterated since its development in the late 1950s. However, at its heart is the same reliable, lightweight, accurate, gas-operated rifle that has remained in military service for over 60 years (as the M16 and M4) and has earned millions of rabid fans among civilian shooters, hunters, and collectors.

A large part of the popularity of the AR platform among firearms enthusiasts is that you don’t need to be a gunsmith to build an AR-15 style rifle. With some basic tools, anyone with a minimum of mechanical ability can assemble an AR from the smallest pin to the largest component. If done properly with quality parts, there’s a 99.9% chance that the rifle will function perfectly and safely. Ideally, you should double-check the headspace with a set of go/no-go gauges, but with the AR, you don’t need to cut/ream the chamber, lap any bolt surfaces, or any other processes common to building other types of rifles.

Of course, this modularity or easy assembly is only possible due to the enormous supply of AR-15 parts, barrels, receivers, bolt carrier groups, furniture sets, and more on today’s market, due to the widespread popularity of the rifle. Before we clue you in on some of the best AR receivers on the market, we need to go over two of the most important considerations a buyer today should be informed about: Should you go with a forged or billet receiver, and should you look for a 6061 or 7075 alloy?

Are forged or billet AR-15 receivers better?

There are three major types of AR-15 receivers on the market today: Forged, billet, and polymer/carbon/composite. Let’s quickly go over the basics of how each is made, and then we’ll briefly touch on the advantages and disadvantages of the primary choices.

Forged receivers are (you guessed it) forged by huge die-forging machines that hammer hot aluminum alloy into the basic final receiver shapes using extremely durable forming dies. These raw forgings are then solution-heat treated, quenched, cooled, and aged to achieve an ideal balance of hardness, strength, and flexibility, and then internally machined by a firearms manufacturer into functional receivers. In the USA, the lower receiver that houses the trigger group is the serialized part, and is legally considered the firearm.

Billet receivers start with rectangular aluminum alloy bar stock that is sawn into blocks, which are then milled using CNC (computer numerical controlled) machines. Essentially, a billet receiver starts as a large block of metal and the machine cuts away everything that isn’t an AR receiver, like a sculptor carving a statue out of marble or wood.

Composite receivers can be made from advanced polymers, a carbon fiber matrix, or today they can even be 3D printed (at least lower receivers can). Commercially produced composite receivers have generally been rare, with only one or two companies actively making them at a time over the decades. When designed and produced intelligently, composite AR receivers have some desirable properties and have earned a few fans. However, due to these receivers’ relative scarcity, for our discussion today we’re going to limit ourselves to forged vs. billet aluminum AR receivers.

Advantages of forged AR-15 receivers

The first AR-15s and M16s were forged, and the majority of AR receivers produced and used by both the military and civilians today are forged. Let’s go over the main benefits of this type of receiver.

• Strength and durability: Forging the alloy into its final shape alters its grain and crystalline structure and results in a stronger receiver, all else being equal.
• Less machining required: Since the forging dies produce the rough external dimensions of the receiver in the forging process, the machining/milling steps necessary to complete a forged receiver aren’t as involved or lengthy when compared to a billet receiver.
• Lower cost: In general, forged receivers can be far less expensive than billet receivers.
• Generally lighter weight: Some specialized lightweight billet receivers have been produced (at great expense), but in general, a typical forged receiver is lighter than the majority of billet receivers.
• Compatibility across the platform: Since both the original military and civilian AR-pattern rifle designs used forged receivers, there is somewhat of a standard design, which the vast majority of companies follow. You’re much more likely to successfully pair one company’s random forged lower receiver with another company’s random forged upper receiver (and parts) than you are to pair billet lower and upper receivers made by different companies, since they can have many more proprietary dimensions and features.

Downsides of forged AR receivers

• Defects in the raw forgings: Though rare, improper forging or heat treatment can cause inclusions, voids, and stress-risers in the raw forgings. However, proper forging and inspection prevents this in nearly all cases.
• Receiver quality depends greatly on final machining: With forged receivers there can be great variations in quality of the finished product depending on how the final machining and finishing processes are performed. The same raw forging could be sent to two different companies for completion, and the result could be one lower receiver that is perfectly within spec and functional, and the other may be out of spec and might not even be capable of having a trigger group installed into it. This has nothing to do with the quality of the forging, but rather of the machining by the final manufacturer.
• Limited customization or variants: Since the overall external shape and surface finish of a forged receiver is determined by the forming dies, this can’t be changed or modified without changing the forging dies and process at great expense. Manufacturers wishing to make significant changes to a forged receiver have to weigh the cost/benefit ratio of creating new dies.
• Supply is dependent on industrial forges: Forged AR receivers must be produced in a specialized metal forging concern, and depending on which sources you read, there are only around 20 forges actively in operation making AR receivers. This includes all of North America and Europe (see below for a list).

Advantages of billet-machined AR-15 receivers

Now let’s go over the pros and cons of a billet/machined AR receiver compared to a traditionally forged one.

• Supply is not dependent on industrial forging concerns: Anyone with a CNC mill and the appropriate CAD drawings can make a billet receiver.
• The alloy material is consistent throughout the entire billet: Since these receivers are milled from a large block of bar stock the grain structure of the metal is consistent throughout and isn’t influenced by the heat/dies/impacts involved in the forging process. This makes it easier for manufacturers to produce a consistent product. However, there are some potential downsides, which we’ll address below.
• Easily customized: With a billet receiver, designs can be easily changed and customized just by changing the computer design program. If you can dream it up and draw it in CAD, the CNC mill can make it happen, for the most part.
• Tolerances can be held tighter: Since billet receivers don’t rely on the variations in dies or heat expansion/contraction during manufacturing, they can be more precisely made than many forged receivers. Commonly, a billet receiver cut by a quality CNC mill can hold tolerances of ∓.005”, or roughly half the thickness of a human hair. For shooters who crave a solid lockup between their upper and lower AR receivers, billet is often the way to go.
• Superior finish: With billet, the external finish can be smoother and more uniform than die forgings, since billet receivers are fully machined on both exterior and interior surfaces. With forged receivers, the final exterior surface is largely how it appears when removed from the dies.
• Potentially stronger in some areas: Billet AR-15 lowers are potentially stronger around the trigger guard ears, takedown pins, and receiver extension threads than traditional forged receivers. Since these areas can be easily beefed-up with the proper CAD design, more material can be left in place to reinforce these points of potential breakage. An integrated billet trigger guard can be thicker and much more rigid than the forged mil-spec, hinged AR-15/M16 trigger guard design, which leaves relatively thin ears where the pins go through and which can break under careless impacts or heavy use.
• Advanced features are more available: Since changes are far easier to make with billet, it’s more common to find billet receivers with advanced features such as side-charging slots, ambidextrous bolt stops and magazine releases, enhanced magazine wells, and more. However, over the past few years, forged receivers are becoming more widely available with advanced features.

Downsides of billet AR receivers

• Less strength and durability: We mentioned above that a properly forged AR receiver will be stronger and more durable than a billet receiver, all else being equal. The forging and heat-treating process strengthens the material, optimizing its grain and crystalline structure. Weight for weight, and using the same dimensions, a forged receiver will generally outperform one carved out of billet. However, as mentioned, billet makers can easily beef up or optimize areas that may be subject to strength issues.
• Greater weight: Generally speaking, billet receivers need to be heavier in order to survive the stresses at key points around the receiver, such as the front takedown/hinge pin and receiver extension ring, compared to a forged receiver. Additionally, since forging strengthens and toughens the alloy, a non-forged billet receiver must generally be a little thicker and heavier overall, if durability is to be maintained. There may be exceptions for ultra-high-end billet designs, but in general, a forged receiver has a weight advantage.
• Greater cost: In the past, billet lower receivers cost at least $250 and increased from there. However, in recent times, there are some manufacturers selling billet receivers as low as $100 or sometimes lower on sale. Generally, though, you can get a forged receiver for less money than a billet. During times of economic or social uncertainty, prices for AR parts and receivers generally increase, but you can often buy forged, stripped AR lowers for $50 or even less on sale. Another way to put it is that a good-quality billet receiver set usually costs significantly more than a good forged set.
• Reduced cross-platform compatibility: Since there are so many variations and customizations available among billet receivers, there is also the issue of reduced compatibility. If you buy a billet lower receiver from one company, there may be an issue with fitment or function if you buy a particular billet upper receiver from another company. This problem also exists to some extent with forged components, particularly when talking about enhanced or proprietary receivers, but the issue is much greater when shopping for billet stuff. It’s usually best to get a billet upper and lower receiver from the same manufacturer to ensure fitment and compatibility (as well as appearance).

Is 6061 or 7075 aluminum alloy better for AR-15 receivers?

By far the most common aluminum alloys used in constructing firearm receivers are 6061 and 7075, both of which are approaching 100 years old and which were initially developed and used primarily for the aviation industry. The original AR-10, AR-15, and M16 rifles were constructed of 6061, but eventually the military transitioned the M16 and subsequent variants to 7075 for the most part. Internet forum arguments on this subject will likely continue until the end of time, but the bottom line is both 6061 and 7075 are suitable for use in construction of AR-15 receivers, though they differ somewhat in their inherent properties.

The 6061 alloy is easier to weld, is less expensive, easier to machine, and more resistant to corrosion than 7075 (though you may find some online armchair metallurgists claiming it’s less resistant to corrosion). 7075 is lighter, stronger, and conducts less heat than 6061. Generally speaking, billet receivers are more commonly made from 6061, since it’s not as hard and is easier to machine. However, there are many billet 7075 receivers available today. You will generally pay a premium for a billet 7075 receiver set compared to a billet 6061 receiver set, due to the increased time and difficulty involved in machining the harder 7075 alloy.

Tempering: T4 or T6?

Perhaps more important than the 6061 vs. 7075 material question is the tempering process being performed consistently and properly. Tempering is vital to proper performance of any metal alloy, and for the aluminum material used for AR receivers, it involves a lengthy and specific process in which the metal is solution-heat treated, quenched, cooled, and sometimes artificially aged to achieve an ideal balance of hardness, strength, and flexibility. This can take up to 24 hours. Tempering to a T4 designation involves the aluminum material being subjected to a solution heat treatment in this temper state, which entails heating the material to a predetermined temperature range and then quenching it in water. This process helps enhance the alloy’s strength and formability. Many AR-15 receivers have been produced over the decades with a T4 temper designation. A T6 temper involves additional artificial aging, during which the material is exposed to controlled temperatures to further enhance its mechanical properties, particularly its hardness and strength. There are exceptions, but today, most 6061 and 7075 alloys intended for the AR-15 receiver are tempered to a level of T6.

Strength of 7075-T6 versus 6061-T6

As far as the properties of each alloy, the tensile strength of 7075-T6 is nearly double that of 6061-T6. The shear strength of 7075-T6 is roughly 1.5 times that of 6061-T6. The former is substantially harder as well. However, 6061-T6 has properties that are well within the requirements and specifications of the AR-15’s design, and a well-made 6061 AR receiver will perform equally well to a well-made 7075 AR receiver in any realistic real-world testing. Today’s AR-15 manufacturers have generally started trending away from 6061 and increasingly moving toward 7075, but that’s not to say that a properly constructed, tempered, machined, and anodized receiver set constructed of 6061 is functionally inferior to one constructed of 7075. 7075 has become the more desired material simply due to its generally superior strength, as well as due to careful marketing by companies that use it. But in actual function there’s essentially no difference for 99.999% of users. In short, the accuracy of the heat-treating, machining, and anodization processes will have a much greater impact on the functionality of the end product than whether it’s made of 6061 or 7075.

What is anodization and why does it matter?

Anodization is an electrochemical process by which the surface molecules of the aluminum are converted to aluminum oxide, which is much harder, resistant to corrosion, and more durable than the raw aluminum underneath. The process also permits the use of various colored dyes to enhance the appearance of the anodized part. Nearly all forged AR-15 receivers are anodized and many billet receivers are anodized, which increases their lubricity and durability. Some high-end billet receivers may be coated with advanced materials that further enhance these properties, or they may not be anodized at all, but rather treated with Cerakote or another durable coating.

Who actually produces raw AR-15 receiver forgings?

There are hundreds of companies that manufacture or assemble AR-15 pattern rifles, including those that complete the drilling, machining, and threading of the receivers, but the vast majority of them don’t have the capability of forging their own receivers. Generally, a separate industrial alloy forging concern is involved in producing the raw forgings, which are then sent to the respective firearms manufacturers for final machining and finishing. Some manufacturers then anodize their completed receivers after machining, and some send them out to specialists for anodization. Regardless, there are relatively few companies who actually create and heat-treat the raw forgings used to manufacture AR-15 receivers.

List of companies that forge AR-15 receivers

Chances are every forged AR-15 you’ll come across was produced by one of the following forges making raw AR-15/M16 receiver forgings (or who have in the past).

• Accurate Forging (acquired by Cerro ca. 2000)
• Alcoa Forge
• ArmaLite
• Anchor Harvey
• Brass Aluminum Forging Enterprises
• Bravo Company Manufacturing (possibly; they may be partnering with a different forge equipped with BCM branded dies)
• Capco
• Cardinal Forge
• Cerro Forge
• Colt’s Manufacturing (including with various partners)
• Continental Machine Tool
• Diemaco
• Emco
• Fabrique Nationale (including with various partners)
• JVP
• Kaiser Aluminum
• LAR Manufacturing
• Lewis Machine & Tool
• Martin Marietta
• Mega Machine Shop
• Mueller Industries
• Olympic
• Performance Forge
• Spartan Forge
• Superior Forge
• Uleven Forge

Top AR-15 upper and lower receivers

Now that we’ve covered some of the basic factors you should consider when shopping for an AR-15 receiver, let’s go over some of our favorites.

BCM (Bravo Company Manufacturing)

Bravo Company Manufacturing was founded by Marine veteran Paul Buffoni in his Hartland, Wisconsin garage, shortly after Operation Iraqi Freedom in 2003. From the beginning, BCM’s philosophy has been to produce the finest-quality rifles and components for the warfighter. At the time, there was a dire need for durable, mil-spec weapons system components for military and private security professionals working in dangerous theaters of operation. BCM considers their firearms to be life-saving tools, similar to a parachute. Every aspect has to be as good as it can possibly be.

For this reason, BCM generally doesn’t offer their forged, 7075-T6 lower or upper receivers for sale as stripped, separate components, though they have made limited runs in the past. To make sure their products perform as designed and are made from quality components, they prefer to offer complete upper receiver groups (including barrel, forend/rail, and bolt carrier group) and lower parts kits (or complete carbines and rifles), starting at $675 for cosmetic blemished upper groups (or as low as $610 without handguards). They also offer their complete lower receivers as cosmetic blems through places like Palmetto State Armory (currently $470). So, if for some reason you want a BCM lower receiver but not any of the excellent parts that come with it, you can buy one of these completed lowers and strip it down to your liking. Complete BCM rifles and carbines start at around $1,500 these days, but if you buy a complete cosmetic blem lower and upper separately, for a little over a grand, you can piece together a top quality firearm and save significant money.

Recently BCM has been offering their forged upper receiver groups with a star-shaped forge marking, which is BCM’s brand logo. However, we’ve been unable to determine with 100% certainty whether BCM is actually forging these receivers in house or has partnered with a forging house that has developed brand-specific BCM dies. We suspect the latter, but truthfully, it doesn’t really matter. BCM has always been known for producing top-quality rifles and components, and whether their receivers are forged in-house or whether they’re made to BCM’s strict specifications has zero impact on the excellence of the final product.

If you’re in the market for a real-world, hard-use AR-15 receiver group or complete firearm, BCM should definitely be one of the first companies to consider.

Aero Precision

Daniel Defense is another manufacturer that has earned a solid reputation for building bomb-proof, battle-ready rifles. It’s often been said that if you’re building an AR and you want the greatest accuracy and performance for your money, you should spend your dough on a good barrel/bolt carrier group and a good trigger. As long as the lower receiver group is acceptably in spec, the above components will really make the difference in accuracy.

So, if you’ve got a lower receiver figured out and are shopping for an upper receiver group, you might want to check out Daniel Defense’s offerings, starting at $1,263 and moving up to $1,698 depending on options and configuration. If you want excellent performance but want to keep things from getting too cumbersome, have a look at the DDM4 V7 LW upper receiver group ($1,263). This streamlined, lightweight upper receiver group includes a lightweight profile, 16”, cold hammer-forged chrome-moly vanadium steel barrel with a 1:7 twist, and a mid-length gas system. The barrel is chrome lined, mil-spec heavy phosphate coated, and HP/MPI tested. The receiver is forged from 7075-T6, while the handguard is milled from 6061-T6 and includes Daniel Defense’s proprietary locking system that helps prevent the free-floated MFR rail from rotating under extreme abuse.

The low-profile gas block is CNC machined of hardened 4140 steel. The included bolt carrier group is an M16 profile, is mil-spec MP tested, chrome lined, with DD’s inevitably properly staked gas key. The whole assembly weighs just 3.9 pounds.

Geissele Super Duty Mod 1 Heavy Barrel

Moving in the other direction from a lightweight upper receiver group, we have the Geissele Super Duty Mod 1 Heavy Barrel upper receiver group ($1,410). Bill Geissele built his company making top-tier triggers for America’s high-speed soldiers and gunfighters, but in recent years has branched out into making complete uppers, lowers, and rifles, including for US special ops groups and other military clients. His design for free floating the barrel and locking down the handguard/rail has been highly praised for its simplicity, durability, and rock-solid performance in combat. Anything Geissele offers will be extremely high quality, but if you like to shoot a lot, and shoot fast, you might favor the Heavy Barrel variant of his Super Duty design. Offered in either .750” or .812” diameter, cold hammer-forged, heavy barrel options, this HB upper will withstand sustained rates of fire while maintaining the accuracy and reliability the Super Duty is known for.

Both the barrel and Forged Stressproof Bolt are high-pressure tested (HPT) and magnetic particle inspected (MPI), and work in concert to achieve superb dependability with match-grade accuracy. The Super Duty features a precisely balanced gas system, including the bomb-proof Super Gas Block and fine-tuned gas port sizing.

The aforementioned, center-tab matched MK16 rail features stainless steel QD inserts to reinforce the sling attachment points for heavy use. The Airborne Charging Handle provides ambidextrous use and accessibility while maintaining a lower profile to eliminate snagging on gear. If you fancy a Gucci AR, Geissele is a must-stop shop.

Honorable mentions for the best AR-15 receivers and manufacturers

The selections above are just some of the top picks we thought most interesting or innovative in our recent review of the market, but if you’re looking for other high-quality AR-15 receivers and/or rifles to consider, be sure to have a look at the manufacturers below:

• LWRC
• SOLGW
• Palmetto State Armory (great for the price)
• Colt
• FN
• Knights Armament
• Noveske (particularly their matched receiver sets)
• Centurion Arms
• LaRue Tactical
• Patriot Ordnance Factory
• Primary Weapons Systems
• Seekins Precision
• Blackout Defense

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