Best M16 A1 Upper Receivers – [2024 Complete Buyer’s Guide]

| Last Updated:
October 3, 2023

Semi-automatic rifles based on the AR platform are the most popular firearms in the United States, and there are several good reasons for it.

The ingenuity of AR design lies in its modularity and easy customization to everyone's body, style of shooting, and sensibility.

As the “Lego Kit of the Gun World”, the AR-15/M16 A1 modular design structure allows the entire rifle to be disassembled by separating the barrel and bolt assembly from the fire control group and magazine well.

Comparison of the Best M16 A1 Upper Receivers

  • This stripped style receiver comes with A1 profile carry handle
  • All standard AR components will work correctly with this upper
  • Brownells M16 A1 Upper Receiver made in conjunction with NoDak Spud is the winner in Best Overall category
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  • Best For The Money is assembled upper receiver from Aero Precision
  • This fully assembled upper works with standard AR-15/M16 components
  • The fully assembled upper receiver includes port door and forward assist
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  • Blem issues are cosmetic, only referring to finish imperfection
  • It features an original A1 profile perfect for a “Retro” or reproduction build
  • In the category of Blemished M16 A1 Upper Receivers, the winner is Brownells
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  • This is forged, Mil-spec A3 flat top upper
  • Aero Precision made the whole series of high quality stripped upper receivers
  • It features .250” takedown pin holes and will accept standard AR-15/M16 components
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  • WMD Guns Upper Receiver has NiB-X coating
  • NiB-X plated parts need reduced effort to clean up
  • Ultra-smooth surface coat for outstanding wear resistance and lubricity
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What is the Role of an Upper?

The M16A1 is assembled of two parts, upper and lower receivers. That concept makes it easy for maintenance and cleaning, but more importantly it allows the whole army of AR enthusiasts to build their own dream rifles.

As we said, the AR- pattern rifle is made up of two parts. The first of those parts, the upper receiver, is the part of the gun commonly made of aluminum that contains and protects the charging handle, BCG (bolt carrier group), barrel, rail system, handguards, and more.

While the complete upper assembly or full upper-half of an AR15 rifle includes all the needed components, a complete upper may come with the ejection port door and the forward assist button. There is also the stripped upper receiver, which is just the solid piece of metal housing all the parts.

The upper receiver of the AR-15/M-16 family of firearms is always vital as it is the heart of your little black rifle. The upper and barrel you choose will determine the remaining parts needed.

Benefits of Upgrading Your M16 A1 Upper

Upgrading your M16A1 upper receiver can offer a lot of benefits because by merely changing the upper you can change a lot of the properties of your M16 without buying a new gun.

An upper assembly combined with a quality barrel and free-floating handguard is essential for gun accuracy. By some researches, you can become up to 45 percent more accurate when you build the rifle with quality upper components and furniture that feels best in your hands.

While the high-quality longer barrel will provide a more accurate long-range shot, the shorter barrels are more maneuverable and offer more versatility in confined spaces.

Contrary to the full upper-half, you can opt for an assembled upper that has no barrel but includes the ejection port door and the forward assist factory installed.

If you consider yourself an AR-15 enthusiast and prefer stripped uppers, then you will need the particular upper receiver parts kit and some experience to get the exact specs and components you want to put in your upper receiver.

For instance, choosing an AR-15 A1 or A2 style upper with a permanently fixed carry handle will determine you to build a "Retro" M-16 civilian version, the hottest new trend in the AR-15 world or allow you to assemble a rifle for use in shooting matches. There are also A3 variants with detachable carry handle or flattop receivers, also known as the "Slick-Sided" uppers. These are ideal for scoping your rifle, granting it immense roles and purposes.

If you plan to pick a budget upper, you should note that they won’t come with the charging handles nor bolt carrier groups and may not have the most advanced handguards.

Budget uppers also often lack accessories that you might demand, or they're not up to the same level of precision machining like some high-end brand uppers.

Quick Take - The Best M16 A1 Upper Receivers

Review of the Best M16 A1 Upper Receivers

There are some tremendous M16A1 upper receivers on the market ranging from those intended for serious LE users and heavy use to budget uppers acceptable for recreational shooters or a starter build. This guide will provide you with an overview of some of the best M16A1 upper receivers on the market.


  • Made of 7075 T6 aluminum forging.
  • Perfect for a “Retro” or reproduction build.
  • Impressive workmanship.
  • Matte black or matte gray hard anodized finish.
  • Stripped upper will accept all standard AR-15 components.
  • Features original A1 profile with carrying handle and without the case deflector.


  • Carry handle groove is not in spec.
  • Grey finish doesn’t fit lower receiver color.

The prevailing trend of cloning military firearms is particularly mirrored in the "Retro Black Rifle" and building an M16A1 clone. For this purpose, Brownells has released M16A1 Upper Receiver made by NoDak Spud, a renowned manufacturer of stunning reproductions of the M16A1 receivers.

The Brownells AR-15/M16 Upper Receiver features A1 profile with a proper carry handle and A1 rear sight housing. There are some negative reviews stating that the carry handle groove is not in spec and the optic mount will not drop in.

This is a completely stripped upper that comes without M4 feed ramps and case deflector like genuine "A1" type. However, it is made up to the correct dimensions to accept all standard AR-15 parts to build your Vietnam era "Slick side" rifle.

This NODAK SPUD receiver is machined from 7075 T6 aluminum forgings with a type 3 hardcoat anodizing in matte gray or matte black finish.

While the gray finish mimics the original anodizing found on the early rifles, some owners complain that the color should be a lighter gray for a proper clone build. On the other hand, the black finish matches most modern lower receivers found on the market today.

Bottom Line

Since the M16 retro market is gaining in popularity, this is an excellent choice for those who are assembling a Vietnam-era M16A1 rifle but demand the correctness in their builds.


  • Has the M4 feed ramp cuts.
  • White T-marked, numbered rail.
  • Forged, Mil-spec A3 flat top upper.
  • Standard .250 takedown pin holes.
  • Dust cover and forward assist already installed.
  • Manufactured using 7075 T6 aircraft-grade aluminum.
  • Hard anodized in dark black M16/AR-15 upper receiver.


  • Somewhat flimsy construction.
  • Dust cover may come incorrectly assembled.

There are many companies offering aftermarket uppers, but there are probably less than a dozen manufacturers that actually machine the upper. The Aero Precision is one of them.

Building its reputation in the aerospace industry with advanced manufacturing technology, Aero Precision has achieved consistent quality and workmanship.

Their model number APAR501603AC is shipped fully assembled, ready to add a barrel, bolt carrier group, and handguard right out of the box.

Unlike stripped uppers, this Aero assembled upper comes with a dust cover, shell deflector, and forward assist factory installed.

At 8.35 oz., the Aero Precision flat top upper receiver is precision machined with high-quality forged 7075-T6 aluminum. Though Aero claims that this part is made to mil-spec M16/M4 specifications, and will drop-in fit onto any mil-spec lower, some AR builders complain at loose construction with a lot of wobbles.

This upper also includes an M4 feed ramp, .250 takedown pin holes and laser engraved T-marks for the rail that readily accepts optics mount or sights.

Although the common upper exterior is Type III hard coat anodized in a dark black finish, it is also available in several colors for a small extra charge.

Bottom Line

The Aero Precision is typical of commonly assembled uppers built to Mil-Spec standards. The Aero AR-15 assembled upper receiver comes ready to assemble with the upper parts kit of your choice and ready to be installed onto any standard AR-15 lower.


  • Compatible with mil-spec AR lowers.
  • Machined from forged 7075-T6 Aluminum.
  • Features M4 feed ramps.
  • Uses .250” takedown pin holes.
  • Matte black hardcoat anodized Mil 8625 Type 3 Class 2.
  • Comes with laser-engraved T-marks and an American flag.


  • Takedown holes can be a bit tight and may need DIY activity.

Featuring high quality and affordable price, the Aero Precision AR-15/M16 upper receiver comes as stripped or complete version and represents the gold standard, an excellent option for most AR builders.

They offer a whole series of stripped uppers without upper parts, enabling you to choose your own forward assist and port door.

Also known as a “slick” upper, this type of upper is a workhorse upper receiver made from forged 7075-T6 aluminum, which can withstand more pressure and stress than billet uppers. The Aero Precision upper receiver is built to M16/M4 specifications including M4 feed ramps for reliable feeds every time operation.

Aero Precision AR-15 stripped A3 flat top upper features MIL-8625 type 3 hardcoat Class 2 anodized finish for excellent wear resistance. While the Aero AR-15 stripped upper receivers are available in different finishes like black, Cerakoted OD green and Cerakoted FDE, their model APAR501602C comes in black color with laser-engraved white T-marks and an American flag on the Picatinny rail.

Although this upper receiver is compatible with all MIL-SPEC AR-15/M16 components and will match most AR-15 lower receivers with a solid and dependable fit, its hole for forward assist and takedown pin holes are little tight and may need a little filing or drilling to spread them out a little.

Bottom Line

With the production of all parts in-house and having control over the manufacturing process, the Aero Precision managed to maintain very high standards of quality control, making their components among the best value on the market.


  • NiB-X provides a smoother action.
  • Features extended M4 feed ramps.
  • High environmental corrosion resistance.
  • Coating eliminates the need for lubrication.
  • Stripped upper from forged 7075-T6 aluminum.
  • Topcoated on the outside with a black ceramic coating.
  • With Rockwell hardness of about 70, NiB-X coating is harder than Chrome Plating.


  • More expensive than uppers with standard finishes.
  • Pivot pin paint is too thick and the pivot pin holes are slightly too small.

WMD Guns is a well-known company for their proprietary high-performance coatings for firearms.

The WMD Guns NIBXUPPER02 stripped upper receiver features enhanced wear characteristics not only because it is machined from 7075-T6 aluminum forgings, but because it is finished in WMD's exclusive NiB-X coating.

As you probably know, nickel boron plating is hard, tough, slick, and smooth, but a WMD new, improved NiB-X coating provides a hardness of 70 Rockwell that is harder than Tennifer, Melonite, or hard chrome plating and has a Coefficient of Friction (CoF) of .08, a tad more than Teflon. The WMD's proprietary NiB-X nickel boron coating is placed inside the upper receiver for exceptional slickness, outstanding wear resistance, and lubricity.

The upper receiver exterior is top-coated with a black ceramic coating (CCB), but it is available also in standard colors like Flat Dark Earth, OD Green, and Stripped Nickel Boron Silver or any other color upon request.

This improved Nickel Boron coating is reliable, even with very little oil because it has a much lower coefficient of friction. Moreover, it offers excellent corrosion resistance, better than chrome plating. The WMD flat-topped stripped receiver comes with .250" Dia. Pivot/takedown pin holes and extended M4 feed ramps for reliable feeding.

The WMD Guns AR-15/M16 NiB-X coated upper receiver is smooth as glass, but the takedown/pivot pin holes are too small, with tight tolerances that may require some filling or using a rubber mallet for installation.

Bottom Line

The WMD fully coated NiB-X AR-15 stripped upper receiver is an ideal building block for a long-lasting AR-15 due to its ultra-smooth and an exceptionally tough nickel boron coating. Specifically engineered for long life, high reliability, and easy cleaning, this coating can withstand over 30,000 rounds without chipping, spalling, or flaking.


  • Fits standard AR-15 components.
  • Blemished upper is fully functional.
  • Made from a 7075-T6 aluminum forging.
  • Correct early-style A1 carry handle contours.
  • M16A1 profile with A1 rear-sight housing.
  • Uses a NoDak Spud Forging.


  • Colors vary greatly between upper receivers.
  • Besides cosmetic blemishes, this product may come with scratches and dents.

The Brownells Blemished M16 A1 upper receiver is perfect for someone who is going to build a faithful reproduction and period-accurate M16A1 rifle. The other reason to get a "blemished" version of the assembled upper is the price tag, as you can purchase this upper for about three-fourths the price of a regular receiver.

These uppers are marked “NDS” which means they are a NoDak Spud forging. Made from rugged 7075 T6 aluminum, these receivers are later machined by the Brownells to the proper profile and protected with a durable hardcoat anodized finish. Due to anodizing issues, these receivers are rejected by quality control, but they meet all the requirements in terms of metal quality and specifications.

On the flip side, while the Brownells list the blemish as "only the finish color" these uppers can have more issues like dents, pits, and scratches.

The upper designated as 078-000-446WB item features an original A1-style shape, original profile carry handle with an A1 rear-sight housing. Since it matches the features of the original M16A1 receiver, the upper comes with no shell deflector and does not have the M4 feed ramps found on most modern-production AR-15 flattop uppers.

Whether you pair this upper with the early rifles or modern lowers found on the market today, all current AR-15 components will work perfectly with Brownells Blemished upper receiver.

Bottom Line

If you’re balling on a budget and want to refinish your AR-15 rifle to period-correct contours of a Vietnam era rifle, the Brownells M16A1 blemished Upper Receiver finished with a matte gray or matte black hard anodized finish is a perfect match.

Aspects to Consider Before Buying

By definition, the upper receiver is a part that attaches to the AR-15 lower receiver and holds the barrel, BCG, and all other components. However, before buying an upper, you should know a few things about them, such as various configurations, different material quality, and proper part finishing.

As for the configuration, you should note that upper receivers come as either stripped uppers, skeletonized uppers, barreled uppers, or complete assemblies. Depending on what type you choose, it will affect both the complexity of building and how much it will cost.

On the flip side, whereas the stripped uppers are the cheapest, barreled uppers will carry a considerably higher price tag, though not quite as expensive as complete uppers.

Materials used in upper construction must be high quality from a reputable manufacturer with appropriate testing marks; you don’t want something of dubious quality under your nose that uses an explosion to fire a 55gr projectile out at 3,200 feet per second.

The upper receiver with an impeccable quality finish is not only an attractive looking piece at the shooting range, but it also provides you with longer corrosion protection, wear resistance, and reliability.


Currently, accessories and parts for AR-style rifles seem to be available at affordable prices, but you should know what to look for in your quest for upgrading your existing black rifle or building a new M16A1.

As one of the most important elements of the rifle, an M16A1 upper receiver has to be a quality one, but it does not necessarily have to be expensive since a lot of gun owners just need a good mil-spec upper.

For those who want perfection and nothing less, there are many great choices to go that extra mile in the higher-end builds but at considerably greater expense.

Michael Lutes

Michael Lutes is the managing editor and owner at Gun Mann. He is a veteran, gun enthusiast, 3 gun competitor, and 2a advocate. Mike has a passion for innovation and education across the industry to create great content, training, and insights from the best and brightest.

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