Best AR-15 Upper Receiver Review 2018

Does the term ‘receiver’ ring a bell? If you’re a shooting enthusiast, that term would surely be familiar to you. However, I’m sure you have heard of the AR-15 term (if you read the newspapers daily). That being said, the Colt AR-15 is one of the most popular rifle, it is a magazine-fed as well as an operated semi-auto rifle. Moving on, the receiver can be broken down into two parts, the upper and the lower.

Both parts play an important role to ensure smooth operation of your rifle, once assembled together. The lower receiver is the part that is marked with a serial number and only can be sold through a licensed firearm dealer. Also, you are required to have an FFL license before purchasing it. Moreover, the lower attaches to the barrel, stock, magazine and pistol grip as well as houses the fire control group which consists of the disconnector, hammer, safety selector and trigger.

The upper receiver on the other hand comes with a modular design so you can customize the design of the handle, bolt, barrel and rail system according to your personal preference. In fact, you are able to customize and modify it by purchasing an upper receiver kit to assemble the upper, based on your own creativity. In the review below, we are going to discuss the top rated AR-15 upper receiver so stay tuned and read away!

How to Assemble an AR-15 Upper Receiver?

Before assembling your upper receiver, it is really important to lube it. You’re lucky if it comes out not dry from unboxing, however if it is, you can use any gun oil to lube it to ensure convenient and smooth assembly later on. Moving on, the first step relates to the forward assist. Some products come with a forward assist already pre-installed, however if it’s not, you can do so with a roll pin.

In terms of configuration, the assist’s flat side must be positioned towards the outside meanwhile the curved part should be on the inside. The roll pin will seat and hold the assembly at a recessed section cut out from the assist (facing the bolt carrier). The whole assembly is then placed in the housing in which you should ensure that it is properly aligned with the roll pin. Once they are properly aligned, use a hammer to secure the pin in place.

The dust cover on the other hand needs to be properly set so it provides enough force to the dust cover as well as keeps it out of the way during firing. The spring can be a hassle at times, hence why, you should insert the retaining rod only halfway, followed by placing the spring in position with a retaining rod. How do you know whether the configuration is right then? Easy- the long spring end should be placed on the dust cover while the short end, on the gun.

Apart from that, there is the barrel, in which the ammunition travels through with high speed, before the projectile is fired out of the muzzle. In lay man terms, it can be said that the barrel is attached to the barrel extension, and locked in place by a barrel nut. For this process, you should get a reaction rod which comes in handy to allow user to rotate the upper while keeping the barrel aligned. In addition to that, you have to ensure that the barrel is aligned with the reaction rod slotted end, followed by sliding the upper receiver to mate with the barrel extension (Tip: It is best to apply some lube for easy insertion).

Once both parts are mated, they are secured into place by the barrel nut. Apart from securely attaching barrel to the upper, you’ll also be mounting the handguards at the barrel nut. Before that, you need to first manually screw the nut (with your hands) in and then with a calibrated torque wrench. As a result of this, it should be well-aligned with your gas tube hole, especially when a good amount of torque is applied.

Moving on to the gas tube, installing it is said to be rather simple. Before that, you should know that a gas tube functions to redirect hot gasses produced from the barrel into the gas key on the bolt carrier group, therefore providing energy to cycle to action. First things first, the gas tube is pinned into place in the gas block.

The gas block on the other hand will slide over the barrel and connect the tube and port. As soon as they’re properly pinned, you are to install them on the barrel. If you’re doing it right, the gas block will align well with the hole in the barrel meanwhile the gas tube will feed through the barrel nut and into the upper.

Besides that, the gas tube should fit into the gas key without any issues, when the bolt carrier is placed inside. Last but not least, you just have to add in the handguards- just screw them to the barrel nut and voila, you’re good to go! Similar to the lower receiver, the upper receiver comes with either the forged or billet construction style. Let’s take a look at the advantages of each styles.

Upper Receiver Style:


The billet construction style is more tedious compared to the forged style. That being said, a lot of time and workmanship must be invested in making the upper receiver using billet style, therefore resulting in its expensive overall price. In addition to that, the billet process includes the metal being CNC machined, then carved from a single billet block into the shape of a solid upper receiver.

In terms of strength, it is weaker than that of the forged method. Nevertheless, it is still able to handle powerful recoils from your AR-15 firearm. The plus point of this style is that you can conveniently make aesthetic changes and modifications, according to your personal preference.


Just so you know, the forged method is one of the most common type of receiver style available. That being said, this process involves hot aluminium or steel metal to be molded as well as hammered to become the standard shape of an upper. On top of that, it is then heat treated to increase its strength and rigidity.

For your information, this construction style produces the strongest receiver. The finishing process includes modifications being made such as holes being drilled, engravings, coatings and sharp edges being smoothened to produce a solid and high quality upper receiver.

Top 8 Rated AR-15 Upper Receiver Comparison Table

Name of ProductStyleCartridgePrice
Radical Firearms Upper AssemblyComplete300 AAC Blackout$$$
V-Seven Weapon SystemsStripped5.56mm NATO$$$
D.S Arms Flattop UpperStripped.223 Remington$$
Colt AR-15 ReceiverComplete.223/5.56mm NATO$$$
Aero Precision Assembled UpperAssembled5.56mm NATO$$$
Midwest Industries UpperComplete223 Wylde$$$
Brownell's Complete ReceiverComplete5.56mm NATO$$$
Seekins Precision SP 223Assembled.223 Remington$$$

Radical Firearms Upper Receiver Assembly

Radical Firearms Upper Receiver Assembly

Radical Firearm’s solid upper receiver comes completely assembled so you don’t have to spend time on making modifications and assembling the upper itself. It is forged, hence it can be said that the product itself is of high quality and endurance, due to the excellent strength from the forged process.  Upon the purchase of this product, you are entitled to a forward assist, barrel nut and ejection port door.

However, it does not include a bolt carrier group and charging handle unfortunately, therefore you need to buy them separately. Moreover, this product is equipped with Radical Firearm’s free float handguard, which features QD points. These QD points are located at various points along its round exterior. In other words, it features small circular holes on the rail in order to accommodate quick detach sling mounts.

Equipped with a solid black finish, this fully mil-spec compliant receiver is said to produce a high quality upper for any shooter. In fact, it has a great fit and finish. In terms of fit, it attaches perfectly to the lower receiver and fires a good number of rounds altogether. In addition to that, it chambers in the 300 AAC Blackout cartridge. The 300 Blackout round don’t have much recoil power however, when compared with the .223 Remington cartridge, it produces a little more recoil due to the heavier projectile.

In terms of operation, this product works on a pistol length gas system. This type of operation system comes in handy if you have a suppressor and plan on shooting subsonic rounds through it, because then it will have enough back pressure to cycle the bolt system. The barrel with a 1:8 twist on the other hand is machined from 4150V chrome-moly steel and has a melonite coating. For your information, the melonite coating vastly enhances the hardness of the barrel as well as improves wear and corrosion resistance.

Besides that, the upper and barrel features the M4 feed ramps as well as A2 flash hider on the muzzle, which is attached via 58-24 threads. In my opinion, this A2 flash holder doesn’t do much to reduce the recoil because the AR-15 platform don’t have a lot of recoil to begin with. Not only that, the dust cover is a little tight so it might be hard to close for the first couple of times.

However, you can fix that problem by applying a good amount of lube at that area. All in all, this 16” flattop, law-enforcement grade, drop-in upper receiver is solid and ready to be mounted to any mil-spec AR-15 lower receiver.

Suitable for:

  • Forged
  • Free-float handguard which features QD points
  • Melonited barrel
  • Pistol length gas system operation

V-Seven Weapons System Receiver

V-Seven Weapons System Receivers

The V-Seven receiver is rather unique because it is constructed from the Type III hardcoat anodized, advanced lithium/aluminium alloy. This type of alloy is proven to be lighter, stronger, more rigid, and has a better corrosion resistance compared to the standard 7075-T6 aluminium. Therefore, its greater strength and durability results in a better ability to handle stress, which is a rather important feature in a firearm.

To be exact, this product is made from 2055 lithium/aluminium alloy, using the billet style. In other words, the alloy is CNC machined and carved from a billet block to the upper receiver shape not to mention, you are able to easily make changes to the product, according to your preference. Weighing 5.8 oz (very lightweight compared to others), it comes with a shiny black finish with the stripped style.

Furthermore, this upper chambers in the 5.56mm NATO cartridge. It should be able to chamber in the .223 Remington, however you should take precautions before doing so, by reading the instruction manual to be extremely sure. For your information, the V-Seven recommends that all components such as pin, screws and springs should be installed with a quality lubricating grease or oil, for smoother working operation.

This enlightened 2055 upper however isn’t compatible with the Geissele MK8 rails, without minor fitting or modification of the rail to the upper. In fact, it has solid M4 feed ramp, or commonly referred to as extended feed ramps. The M4 feed ramp extends beyond the end of the barrel extension and has a deeper cut through the upper which comes in handy to aid in feeding rounds into the chamber from the magazine, with maximum ease.

In addition to that, this AR-15 accessory is equipped with an ultra-light port door and one-piece rod. When you put it on the rail, you will observe that the rod is pressure fit and tightly secured. That being said, it has a rather interesting design, however the rod should be installed prior to the barrel nut. Just so you know, the barrel nut functions to mate the upper receiver to the barrel extension for a secure fit, when the right amount of torque is applied.

Suitable for:

  • Billet 2055 lithium/aluminium
  • Ultra-light port door
  • One-piece rod
  • Stripped with black finish

D.S. Arms Flattop Upper

D.S. Arms Flattop Upper

Equipped with a rugged matte black finish, the D.S. Arms M4/A3 style upper receiver is stripped. In other words, a stripped upper refers to the bare upper itself without the barrel, dust cover and bolt carrier group. The upper is hardcoat anodized which comes in handy to add strength, resist wear as well as protect it from corrosion in the long run, therefore contributing to its durability.

On top of that, its hard dry-lube surface treatment plays an important role in protecting the anodizing from scuffs, not to mention reduces friction between the receiver walls and bolt carrier groups, in order to ensure lesser wear, an ultra-smooth operation and a longer service life altogether. Not only that, this product chambers in the .223 Remington cartridge which is a rather popular round used especially for the AR-15, with the exception of the 5.56mm NATO.

In terms of construction, the upper is machined from the 7075-T6 aluminium alloy forging which offers excellent strength to handle batteries of thousands of firing cycles. In fact, it is forged to USG dimensions as well as is ready to mate with the mil-spec lower and any internal component of your choice. The forging construction style further contributes to its superb strength as the alloy is molded and hammered into shape.

Apart from that, it includes the M4-type feed cuts together with the alphanumeric position markers which are stamped into the rail slots. Therefore, when choosing the right barrel to pair with this upper, you need to get a barrel with the M4 feed ramp barrel extension, which is common in many mid-length gas system. Thus, it can be said that the barrel extension determines the compatibility.

The M4 feed cuts on the other hand are more extended compared the standard ones so you can eliminate any possibility of feeding problems or malfunction of the rounds from the magazine, into the chamber. Not only that, it includes .250” takedown/pivot pin holes so you can attach both the upper and lower together with absolute precision.

All in all, the D.S Arms upper has a great fit and finish. Also, it comes with a forward assist pre-installed. For your information, the forward assist is used for manually pushing the bolt carrier forward, in order to seat the round in the chamber. This especially comes in handy in the case where there happens to be a malfunction, and the bolt carrier group don’t seat fully and lock in the battery.

Suitable for:

  • 7075-T6 aluminium alloy forging
  • Has forward assist
  • M4 feed cuts
  • Alphanumeric position markers
  • Stripped M4/A3 upper

Colt AR-15 Receiver (LE6921CK)

Colt AR-15 Receiver

The CK in this product stands for ‘conversion kit’. In other words, it means that this upper comes with the ability to fit any mil-spec Colt lower receiver. For those of you who possess lower receivers with either large or small pins, this conversion kit allows you to fit it to pretty much any Colt mil-spec lower, much to your added convenience.

Upon the purchase of this product, it comes with a charging handle, bolt carrier group, back-up sights, forward assist and an ejection port cover, handguard and front sight. In fact, it can be said that the upper comes with a complete assembly so you just have to focus on attaching the upper and lower together.

For your information, an ejection port cover is used to keep the dirt and debris from entering the bolt and upper meanwhile the charging handle functions to pull the bolt carrier group back to open the bolt for loading, unloading or clearing the firearm if in any case it gets jammed up.

Moreover, this product has a rather interesting rear sight feature in which it comes with a ladder design. This ladder design comes in handy to allow for windage and elevation adjustments to improve the accuracy of your shot. Once the gun has been zeroed in, you just have to click it and therefore, you can view the various yardage marks well. I can vouch that this upper receiver is a must-have as it kept me going continuously for many rounds, not to mention providing accurate shots with tighter groups.

Moving on to the barrel, it features a 14.5 inch barrel with 1/7 RH twist. The barrel is strong and durable as it is M4 cut and chrome-lined. Since it is M4 cut, it can easily accommodate the M4 feed ramps. The chrome-lined material on the other hand is a good pick in my opinion because it offers superior corrosion resistance, ease of cleaning and extended barrel life. I personally love the ‘ease of cleaning’ feature because the barrel needs to be frequently cleaned after each shooting session.

A standard screw-on flash hider is also included with this upper. The screw-on method makes it extremely user-friendly, for your added convenience. Just so you know, a flash hider or also known as a flash suppressor is attached to the gun’s muzzle to reduce visible flash due to the burning gases that exits the muzzle upon firing a shot. Also, it has stamped T-markings on top of the rail.

Suitable for:

  • Screw-on flash hider
  • CK feature
  • Chrome-lined M4 cut barrel
  • Stamped T-markings

Aero Precision AR-15 Assembled Upper (No Auto Sear Cut)

Aero Precision AR-15 Assembled Upper (No Auto Sear Cut)

Aero Precision is known to tend well to their customer needs with one of the proof being this ‘no auto sear cut’ upper receiver. Let’s say you want to get AR-15 accessories, but don’t have the legal documents to possess it, especially for the standard ones that function with an installed auto-sear in the lower receiver. But not to worry, this Aero Precision AR-15 upper receiver with no auto sear cut will be the perfect product for you and is able to cater your needs.

That being said, this product is said to match every specification of a standard upper, including having an ejection port cover, dust cover as well as forward assist (assembled style). Just so you know, the assembled style is often in between the stripped (bare) and complete assembly. The difference between the assembled and the complete is that the complete assembly usually comes with a charging handle and bolt carrier group.

In terms of construction, it is forged from the 7075-T6 aluminium metal therefore contributing to its excellent strength and corrosion resistance. Not only that, it is available either in the black or dark earth finish, which you can choose according to your personal preference. This product chambers in the 5.56mm NATO cartridges as well as is machined with the .250” takedown pin holes which attaches the upper and lower receiver together.

The forward assist comes with a screw instead of a roll pin. Deemed rather convenient and easy, you just have to fix it by either screwing or unscrewing the screw hence you don’t have to worry about slamming the roll pin in and potentially marring the finish of the upper. Meanwhile, the contours of this product are nice and clean.

Besides that, the barrel nut is already pre-installed and machined into the upper. Therefore, building the upper will be a piece of cake. Just so you know, the barrel nut functions to tighten the barrel rod to the upper, therefore locking it into place. On top of that, it comes with the M4 style feed ramps as well as laser engraved T-markings. I personally like the M4 style feed ramps because it aids in smoother feeding operation.

Suitable for:

  • Nice and clean contours
  • Laser engraved T-markings
  • M4 style feed ramps
  • Screw for forward assist (instead of roll pin)

Midwest Industries (MI) Upper Assembly

Midwest Industries (MI) Upper Assembly

This product model is MI’s very first complete upper receiver. That being said, this upper comes with a solid 16-inch barrel with 1:7” twist that is ready to be installed on any mil-spec lower of your choice, according to your preference. It chambers in the .223 Wylde cartridge and is ready to shoot on any military type rifles with equal accuracy.

Equipped with a shiny black finish, it includes MI’s very own lightweight, free-float, M-LOK G3 handguard which comes in handy to accommodate plenty of accessories. In other words, it provides great accessory mounting versatility. One of the advantage of using a free floating handguard is that you are able to make them longer than the gas system length, simply by using a low profile gas block.

Moreover, it sports a forward assist and 2-port muzzle brake that is mounted on the threaded muzzle. The muzzle on the other hand includes the new MI AR-15 flash hider impact device and MI low profile gas block with diameter of 0.75”. Both accessories are manufactured from the 4140 hardened tool steel, therefore contributing to its durability in the long run. However, it doesn’t include a charging handle or bolt carrier group.

The upper is made from the 7075-T6 forged aluminium where its thick walls contribute to great strength and rigidity. It should be very strong so that it is able to handle stress and powerful recoils, when the rifle is fired. On top of that, its barrel is FN medium contoured, hammer forged and chrome lined which comes in handy to extend barrel life and increase corrosion resistance.

Apart from that, it includes a gen2 proprietary barrel nut which is rather versatile as it accommodates either the K-series, G2SS or G2 T-free floating handguards. Not only that, the upper is equipped with an additional T-slot, T0 which is ideal to accommodate a fixed sight or to achieve proper eye relief for certain optic platforms such as your ACOG scope. That being said, it has mil-spec 1913 rail laser-etched numbering in T-slots.

It features the M4 style feed ramps meanwhile the versatile 1-8” rifling stabilizes a wide variety of bullet weights. Last but not least, this product operates on the mid length gas system which usually has barrel length between 14-20 inches and port distance of 9 inches altogether.

Suitable for:

  • Free-float M-LOK G3 handguard
  • Laser etched numbering in T-slots
  • Mid length gas system
  • M4 type feed ramps
  • 2-port muzzle brake

Brownell’s AR-15 Complete Receiver Keymod

Brownell’s AR-15 Complete Receiver Keymod

First things first, you should know that this product, manufactured from Brownells itself, chambers in the 5.56mm NATO cartridge. For your information, the 5.56mm NATO round is one of the two popular rounds used to chamber in the AR-15, with the latter being none other than the .223 Remington.

Weighing 4.85 ounces, it comes completely assembled with a black finish. The completely assembled term refers to the upper receiver assembly that includes that whole package consisting of the bolt carrier group, low profile gas block, charging handle, ejection port cover, forward assist therefore contributing to an outstanding upper receiver product.

However, you should bear in mind that the bolt carrier group is of the M16-style. Therefore, it won’t work with the older Colt lowers that comes with a sear block. For your information, the ejection port cover keeps the dirt and debris out of the bolt and upper. The cover is held closed with a detent spring and opens up under spring pressure, each time the bolt moves forward or rearward.

Furthermore, the 16-inch standard M4 carbine length barrel is equipped with a standard M4 contour with 1:8 twist. In addition to that, the 416R steel barrel of the 7075 aluminium mil-spec upper also has black nitride finish on the interior and exterior, for long lasting performance and extended service life.

This standard A3 13-slot aluminium flattop receiver also includes a 10” free-float handguard that utilizes the Keymod rail system. For your information, the Keymod refers to a universal interface system for firearm accessories that is designed to supersede the MIL-STD-1913 accessory rails. Not only that, this rail system has a modular design, with accessories and rails that can be removed as well as attached at specific attachment points, according to your preference.

That being said, this A3 flattop upper will attach to almost any standard AR-15 lower and is carefully machined to mil-spec dimensions. Besides that, it features M4 feed ramps as well as the standard A2 birdcage style threaded flash hider.

Suitable for:

  • A3 13-slot aluminium flat top receiver
  • A2 birdcage style threaded flash hider
  • M4 feed ramps
  • 416R steel barrel with black nitride finish
  • 7075 aluminium mil-spec upper

Seekins Precision SP223 Upper

Seekins Precision SP223 Upper

I’m sure you have heard of the Seekins Precision brand because the lower receiver of this brand sells like hot cakes. Hence, you can get this upper receiver to pair it with the SP lower so it will most likely be a perfect and tight fit. Equipped with a black finish, this product chambers in the .223 Remington cartridge, which is a rather popular round used with the AR-15.

In terms of style, this upper is not completely assembled. In other words, it comes with an ejection port cover and forward assists pre-installed. For your information, the forward assist comes in handy to manually close the bolt completely in battery if there is a malfunction, where the BCG don’t seat fully and lock in the battery.

Moreover, this product is said to be compatible with any standard pattern AR lower receiver as well as most mil-spec aftermarket rail system such as the mil-spec 1913 Picatinny rail. Weighing 11.2 oz, this uniquely-sculpted receiver is machined and carved from a solid billet with extra metal in critical areas to provide added strength and rigidity. To be exact, it is machined from 7075-T6 aluminium and Type III Class 2 hardcoat anodized for superior wear and corrosion resistance.

This product includes M4 feed cuts, or also known as extended feed ramps which comes in handy to ensure reliable feeding of the ammo into the chamber. I personally like the part where it comes with a set screw instead of a roll pin in order to retain the forward assist, which prevents any potential marring of the finish. All in all, this upper receiver is said to have a top notch fit and finish.

Suitable for:

  • Machined from solid billet
  • M4 feed cuts
  • 7075-T6 aluminium
  • Hardcoat anodized
  • Has ejection port cover & forward assist


All in all, it is extremely essential to get a high quality upper receiver to pair up with your lower to form a solid and powerful AR-15 rifle. Therefore, I hope my review assists you in making the right choice. Happy shooting!

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