Best M16A2 Upper Receivers – 2021 Review Round-up

| Last Updated: June 3, 2021

An M16A2 upper receiver is one of the most important components of any rifle build.

It is also one of the most fun to choose because it lends your rifle most of its unique style.

With so many options to choose from, finding the right M16A2 upper can be very hard. Follow our guide to the best options out there.

Comparison of the Best M16A2 Upper Receivers

  • Includes M4 feed ramps and a barrel finished in Melonite.
  • Free float handguard with M-LOK slots to attach any modern accessory.
  • Bolt is constructed with the best methods, parkerized and chrome-lined.
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  • Includes a forward assist and a dust cover but no barrel.
  • Comes in your choice of two colors, black or cerakote FDE.
  • Comes with M4-style feed ramps for reliable jam-free feeding.
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  • The Picatinny flat top rail is engraved with T numbers.
  • Covered by a lifetime warranty against any defects in manufacturing.
  • Features an enlarged ejection port for compatibility with 458 SOCOM.
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  • Made in the USA and covered by a lifetime warranty.
  • Features an enlarged ejection port meant to accommodate any caliber.
  • Features a unique non-reciprocating design with a left side charging handle.
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  • Includes a Magpul MBUS flip-up rear sight on the rail.
  • All parts and components adhere strictly to military standards.
  • Made in the United States and covered by an unlimited lifetime warranty.
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Are All M16A2 Uppers The Same?

There are various design features that you need to select from when you are choosing an upper receiver. First, there is the manufacturing process. The main distinction is that between forged and machined upper receivers. Forged are often considered stronger than machined uppers because the molten aluminum is smashed into shape with a mold, which crystallizes and aligns the metal into the strongest arrangement.

However, machined uppers are cut from billets of aluminum which were originally formed using a similar procedure. Forged uppers also undergo CNC machining to reach the best tolerances and compatibility with other components. The A2 comes with a removable carry handle and a Picatinny top rail. While the A2 specification stipulates very specific requirements, there are variations in the design of the rear sight and other components.

Why You Should Upgrade Your M16A2 Upper

There are many reasons to upgrade your M16A2 upper receiver. First, you might have an aesthetic reason. Your old upper receiver could be starting to look a bit beaten up or you might have gotten tired of the styling. There is a huge range of design variations with the M16A2 to choose from, especially among machined uppers.

You can also find finishes in a variety of colors to spice up the looks of your build. Another reason is the improved functionality. If you have put thousands of rounds through your old upper, it will have started to wear, reducing reliability and accuracy.

A new upper can return your rifle to peak functionality. A new upper can also give you an alternate platform for use in specific scenarios without the cost of a full separate rifle. This could include the use of a nonstandard caliber or separate sighting setups.

How We Chose Our Favorite Uppers

As usual, the first thing to look for in a new M16A2 upper receiver is that it is a proven model manufactured by a reputable, well-established company. There are endless brands to choose from, although many actually outsource their upper manufacturing to one of a very few receiver fabrication shops. Knowing which to trust can help you choose the best upper possible.

Aero Precision - Assembled Upper Receiver

There are two main materials used for making M16A2 receivers. The most common and better option is 7075-T6 aluminum alloy. It is slightly stronger than the alternative, 6061-T6 aluminum alloy.

Besides this, there are a few styles of uppers to choose from based on personal preference, and we have tried to include the best from each such category. These are stripped versus complete and including a forward assist and without one. Value for money is also a major consideration.

Review of the M16A2 Upper Receivers

Choosing the best M16A2 upper receiver can be a time consuming and confusing process. Luckily, we have put in the time so that you can simply follow our list for the best options out there.

Best Overall:
 Aero Precision - Assembled Upper Receiver


  • Features M4-Style Feed Ramps for Reliable, Jam-Free Feeding
  • Available in Your Choice of Two Colors, Black or Cerakote FDE
  • Comes With a Forward Assist and a Dust Cover But No Barrel or Handguard


  • Occasional Quality Control Issues

Aero Precision was founded in 1994 in Tacoma, Washington, where it is still based. They focus on producing mil-spec AR-style rifles, parts, and accessories. This receiver comes with the forward assist and port door pre-installed. The receiver has been machined from standard 7075-T6 aluminum alloy to exacting M16-M4 mil-spec specifications. It does, of course, have M4-style feed ramps.

The receiver comes in two colors, black and cerakote FDE. The black model features laser engraved T marks on the top rail but the cerakote version does not. The takedown pin holes are .250 inches. Overall, this upper receiver weighs 8.35 ounces.

It is entirely designed and produced here in the USA. This is an excellent option if you want to build your own fully functional modern sporting rifle with a high degree of customization.

Although it comes with the forward assist and dust cover, you are free to choose the barrel, handguard and other accessories that work best for you. This goes for internal components as well, the choice of bolt carrier group and the charging handle is entirely up to you.

Bottom Line

This upper receiver is an excellent option if you are on a budget. Its top features are the M4 style feed ramps, the choice of colors and the complete set of internal components. It is a great option if you want to choose a separate handguard and barrel.

2. Cross Machine - Billet Upper Receiver


  • The 1913 Picatinny Flat Top Rail Comes Engraved With T Numbers
  • Features an Extra Large Ejection Port For Compatibility With the 458 SOCOM Caliber
  • Backed Up By a Lifetime Warranty Against Any Defects in Materials and Manufacturing


  • Occasional Issues With Quality Control

Cross Machine Tool Company is a veteran-owned business operating out of Tennessee. This upper receiver is precision machined to fit any mil-spec lower receiver and to be compatible with any mil-spec parts. It is a machined upper made from a billet of 7075-T6 aluminum alloy, the connoisseur's choice. This alloy is around 65% stronger than ones made of 6061 alloy.

Cross Machine is proud of their five-axis CNC machining setup, which saves time and allows for greater accuracy in workmanship. The receiver is finished in type III class II mil-spec hard coat anodization.

The 1913 Picatinny flat top rail is engraved with T numbers. The forward assist and dust cover port are machined into the receiver, but the assemblies are not included. It also includes a shell deflector.

The walls are slightly thicker for greater rigidity. The ejection port is enlarged to be compatible with the 458 SOCOM caliber. This receiver is covered by a lifetime warranty against manufacturing defects. This is a great choice giving you a high degree of customization on a full-featured black rifle build.

Bottom Line

This is a great option if you want a stripped upper to maintain full control on how your rifle is customized. The top features are the extra-large ejection port, the lifetime warranty, and the T-marked Picatinny rail. If you're a tinkerer who wants quality, this is for you.

3. Gibbz Arms - Side Charging Upper Receiver


  • Made Here In the USA and Backed Up By a Lifetime Warranty
  • Features An Extra-Large Ejection Port Capable of Accommodating Almost Any Caliber
  • Engineered to Have a Unique Non-Reciprocating Design With a Left Side Charging Handle


  • Rare Issues With Fit May Arise

Gibbz is run by the Gibbens family of Meza, Arizona. This non-reciprocating upper receiver has an ejection port which has been enlarged to work with any caliber from .22 LR to .50 Beowulf. It also features Gibbz's unique proprietary left side charging handle. It is compatible out of the box with practically any bolt carrier group, whether mil-spec or custom.

It is also compatible with almost any lower receiver, especially mil-spec ones. It is finished in Melonite. The ejection port has been beveled for smooth looks and operation. The Picatinny top rail has 15 slots. Gibbz has designed their own improved cam-pin to work specifically with their side charging upper.

This receiver features a charging handle cover to keep the gases away from your face. It weighs exactly 13 ounces. This receiver is completely designed and manufactured in the USA and covered by a lifetime warranty. This a good option if you want a highly-customizable upper with the unique benefits of its non-reciprocating feature. If you want to stand out a bit at the range, this one will definitely attract some attention.

Bottom Line

This is a very unique option. The top features are the non-reciprocating design and the left side charging handle. The wide caliber compatibility is great too. If you want to draw attention at the range this is a great option for you.

4. PSA 16" Mid Length 1/7 Nitride 15" Lightweight M-Lok Upper with MBUS Sight Set, BCG, & CH


  • Comes With M4 Feed Ramps and a Barrel Finished In Rugged Melonite
  • The Free Float Handguard Has M-LOK Slots So You Can Attach Any Modern Accessory
  • The Bolt is Manufactured Using the Best Methods, Parkerized Outside and Chrome-Lined Inside


  • Shooters Sometimes Find That the Gas Block Was Installed Wrong

Palmetto State Armory is a major domestic retailer of firearms and firearm components. They focus on the modern sporting rifle market. Given their dominant role, they have an enviable wealth of market data on what firearms, parts and accessories are popular, functional and reliable. They use this data to design and produce many of their own components and complete firearms.

These are often some of the best value for money that you will find anywhere. This upper receiver has a 16-inch barrel with an A2 profile and a standard 1:7 twist rate. The barrel is finished in Melonite. It includes an M4 barrel extension and a mid-length gas system and a low-profile gas block.

The upper comes with a light free float handguard with M-Lok. On the end, there is an A2 flash hider. The upper is forged from a standard 7075-T6 aluminum alloy which has been hard coat anodized. It is cut with M4 feed ramps.

These upper receivers are designed and manufactured in the USA. The bolt is made from shot-peened mil-spec Carpenter 158 steel. The carrier is parkerized on the outside and chrome-lined on the inside.

Bottom Line

The best features of this upper are the M-LOK handguard and well-designed bolt. You can't beat the value for money of this option.

5. PSA 16" Carbine Length 5.56 NATO 1:7 M4 Nitride MOE Upper - with Rear MBUS, BCG, & CH


  • Comes With a Magpul MBUS Flip-Up Rear Sight Mounted On the Rail
  • All Of the Parts and Components Strictly Conform to Military Standards
  • Made Here In the USA and Backed Up By An Unlimited Lifetime Warranty


  • Occasionally Ships With Minor Flaws

As noted above, Palmetto State Armory is one of the safest choices in the black rifle market. This model comes with a barrel made of 4150V chrome moly vanadium that has a nitride finish. It has a standard 16-inch length and a 1:7 twist rate. It comes with a carbine-length gas system, an M4 barrel extension, and a handguard.

The gas block sight base is F marked. An A2 flash hider sits on the muzzle. The upper receiver is forged from standard 7075-T6 aluminum alloy. It has a mil-spec A3 design and is hard coat anodized for resilience. It is also made in the U.S. The bolt carrier group has a full-auto profile.

The bolt is made of Carpenter 150 steel to meet military specifications. The bolt has been shot-peened, high-pressure tested and particle inspected. The gas key is hardened, staked and fastened with grade 8 screws. The 8629 steel M16 profile carrier is chromed inside and phosphate-coated on the outside. This upper includes a Magpul MBUS flip-up rear sight, made in the USA.

Bottom Line

Palmetto State Armory is always an excellent choice for value for money. The top features of this upper receiver are the included rear sight and the rigid mil-spec standards followed in manufacture. You simply can't go wrong with a PSA upper, especially given their outstanding warranty.


We are sure that our list of the best M16A2 upper receivers will save you the time and headache of finding the best option for you. Whether you want a new style, better functionality or just a change for the hell of it, we have the solution for you. Shoot safe and have fun.

Josh Lewis the managing editor at Gun Mann and when he isn't writing about guns he is more than likely tinkering with them. He also enjoys hunting, fishing and spending time outdoors. As a lifelong gun owner he knows his stuff!

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