13 Best AR15 Upper Receivers [Updated 2024]

Looking to upgrade your AR15? This guide showcases 13 best AR15 upper receivers 

These top-rated AR15 uppers are equipped with reliable handguard systems, various barrel lengths, and durable gas systems.

Note: Not all complete uppers include BCGs.

Best AR 15 Upper Receivers

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Sons Of Liberty M89 13.7" Pinned NOX - Best Tolerance

The Sons Of Liberty 13.7" barrel upper with a pinned NOX muzzle device is a highly sought-after complete upper assembly that frequently experiences stock shortages. You can purchase it directly from SOLGW or Primary Arms. What sets this upper apart is its exceptional attention to tight tolerances, a feature often overlooked by many companies.

CMV Barrel -  This durable barrel is designed for long-lasting performance, making it suitable for intense training sessions or as a reliable choice for plinking at the range.

M89 Handguard - The M89 handguard minimizes deflection, ensuring that your laser remains zeroed in. Its extended barrel nut design enhances rigidity, maintaining precision.

NOX Flash Hider - The NOX flash hider is securely pinned to the 13.7" barrel, effectively extending the total barrel length to a legal 16 inches.

Daniel Defense MK18 - Best CQB SBR Upper

The DDMK18 stands out as the premier AR15 complete upper receiver choice for those aiming to construct a 10.3" carbine build with the optimal carbine length gas system. What sets this upper apart is the renowned DD RIS II free float rail system, which boasts a robust Bolt-Up system and provides a generous 9.55" of Picatinny mounting space for M1913 rail accessories and an M203 grenade launcher.

Rigorous USSOCOM Testing - This upper has undergone extensive testing by the US Special Operations Command as part of the SOPMOD II program and meets the stringent combat-grade requirements set by the US Department of Defense.

Authentic, Non-Clone Upper - Unlike other AR15 upper builds that attempt to mimic military specifications with various parts, the DDMK18 is the real deal. It's ideal for SBR (Short-Barreled Rifle) builds or MK18 pistol builds, offering genuine military-grade performance.

Exceptionally Durable Barrel Nut System - The RIS II handguard securely locks onto the receiver using Daniel Defense's patented anti-rotational Bolt-Up system, featuring Grade 8 fasteners. This robust construction ensures the upper can withstand rough handling, drops, and impacts.

PSA BLEM JAKL - Best SCAR Hybrid Build

The PSA JAKL is a unique hybrid complete upper combining elements of both the AR15 and AK platforms. It utilizes a long-stroke piston gas system, operated by an ambidextrous side charging handle akin to the FN SCAR.

Adjustable Gas Block - The upper is equipped with an adjustable gas block, allowing for the use of suppressors. This feature provides versatility in managing gas pressure.

Tool-Free Disassembly - Disassembling the PSA JAKL upper is quick and straightforward, requiring no additional tools.

Compatibility - The upper is compatible with any standard AR15 lower receiver. However, users opting for the PSA JAKL upper must pair it with the PSA buffer system designed for the lower receiver.

Buy JAKL Buffer adapter here

BCM MK2 w/MCMR 15 - Best Barrel Nut Mounting System

The BCM MK2 stands out as one of the finest AR uppers available, featuring the lightweight MCMR rail system that securely attaches the handguard to the receiver using an anti-rotational tab, effectively preventing any shift due to heat, vibration, or rough handling.

It's one of the best upper receiver set for a low budget AR build or a high end build

M4 Feed Ramp - The inclusion of M4 feed ramps on the barrel aids in smoother feeding of rounds, particularly those with more pointed bullet designs, from a magazine into the chamber.

MLOK Mounting Slots - The MCMR 15" rail boasts a full-length MLOK mounting slot system, recognized for its strength and reliability, making it an ideal choice for attaching various accessories.

Palmetto State Armory 10.5" NATO - Best AR 15 Upper For MK18 Build

This AR upper is a top choice for those assembling a 10.5" carbine gas length rifle from PSA. Notably, this upper receiver package does not include a BCG (bolt carrier group) or charging handle.

High-Quality Construction - The upper receiver is precision-machined from 7075 T6 A3 aluminum, meeting MIL-SPEC standards for reliability and durability.

Barrel Excellence - The barrel is made from chrome moly vanadium steel and boasts a 1 in 7" twist rate. Additionally, the upper includes a traditional F-marked front sight post and an A2 flash hider.

PSA's Commitment to Value - PSA is a well-regarded high-end gun manufacturer focused on the civilian market. They maintain a cost-effective approach by handling all aspects of production in-house, reducing middleman costs. This approach allows them to offer exceptional quality at a competitive price.

Aero Precision M4E1 Enhanced - Best Selling

We selected the Aero Precision M4E1 enhanced upper because Aero Precision is a trusted name in custom AR builds. Their M4E1 complete lower is equally renowned as the upper assembly. What sets it apart is their exceptional engineering, which has streamlined the process of mounting a free-floated handguard to just 8 screws.

Furthermore, this system is not only stronger but also lighter, promoting more efficient cooling. These factors make it an excellent choice for AR enthusiasts seeking top-notch quality and ease of assembly.

Aero Gen 2 Handguard - It features include the addition of quick disconnect sling sockets, enhanced milling design for grip and visual appeal and a new profile for the picatinny top rail.

• Handguard mounting platform is forged into the receiver
• Works with Aero Precision handguards but also fits most BAR-system handguards
• Compatible with low profile gas blocks

Geissele URGI Upper - Best Durability

This is the URG-I (Upper Receiver Group Improved) specially designed for the US Army Special Operation Command (USASOC), making it stand out in terms of military-grade performance and features.

Super Modular Rail MK 16 - The primary attraction of this upper is its Super Modular Rail MK 16, an advanced free-float handguard (resembling the BCM MCMR rail but enhanced). This handguard offers exceptional rigidity and modularity, featuring anti-rotation tabs that guarantee the rail remains stable, even under the harshest conditions.

M855A1 (AB57) Ammo Capable - The cold hammer-forged barrel is engineered to withstand the heat and wear associated with the M855A1 (AB57) ammo, known for its higher pressure and increased penetration capabilities against armor and hard targets. This ammo also burns faster, generating more pressure while reducing flash. Its consistent yaw and stable flight performance make it a reliable choice.

Enhanced Mid Length Gas System - With an enlarged gas port and a mid-length gas system design, this rifle experiences reduced recoil and parts wear. Additionally, the over-gassed system aids in overcoming malfunctions.

Pinned Gas Block For Increased Durability - The inclusion of a pinned gas block, a feature commonly found in high-end ARs designed for rigorous use, ensures the gas block remains secure and in place under all circumstances.

Geissele Super Duty Upper - Best Handguard Alignment

The Geissele Super Duty upper receiver features the same MIL-SPEC quality parts as the URGI Upper recommended above.

The only unique difference is the handguard snaps right into the upper receiver like a LEGO piece providing a even better SMR MK16 handguard alignment without anti rotation tabs or setscrews.

The upper receiver is Geissele's proprietary product for their Super Duty rifle line, and you can also purchase their complete stripped receiver set here

Note: Geissele Super Duty Upper receiver and handguard are not currently for sale separately. So getting the complete upper is the best option.

• Perfect handguard to receiver alignment
  
• Even better "No tilt" handguard design 
• Full length MLOK mounting spots including 45 degrees
• Ensures mounted visible or IR laser accuracy relative to the bore

AR57 MFG - Best 5.7X28 AR Upper

This complete 16" AR57 upper transforms any AR15 lower into a rifle compatible with the 5.7X28 caliber, akin to the FN P90. Its distinctive design loads bullets from the top and expels spent shells through the standard AR15 lower receiver magazine well.

Additionally, users have the option to mount various optics on the 13-slot Picatinny rail located on the receiver. This upper offers a unique and versatile shooting experience.

MLOK Handguard - Mount any MLOK accessories 

Material - 8620 Alloy

Knight's Armament URX SR15 - Best Old School

While the SR15 upper may appear similar to other AR15 uppers externally, it offers a unique Bolt Carrier Group (BCG) system with rounded bolt lugs. These rounded lugs not only enhance shear strength but also make unlocking the bolt easier after a round is fired, resulting in a firearm that is both durable and delivers reduced recoil.

Enhanced Dual Spring Ejector - The dual spring system boosts the clamp force on the shell casing, ensuring reliable extraction after each shot, contributing to the upper's reliability.

But there is more...

Improved Dual Spring Ejector - The dual spring system increases the clamp force on the shell casing to ensure reliable extraction after each shot

Rock Solid URX Rail System - Sleek Appearance and Robust URX Rail System - The URX rail system strikes a balance between aesthetics and sturdiness. It strategically places Picatinny rail sections at popular mounting locations on the handguard to minimize weight. Additionally, it incorporates QD (Quick Detach) mounting slots for sling attachment, with the URX 4 MLOK rail system being the current favorite among users.

Radian Weapon System Model 1 - Best Low Recoil Mid Length Upper

This 14.5" barrel equipped with a mid-length gas system stands out as one of the most preferred choices for a low-recoil upper, even when compared to offerings like the Geissele URGI. Additionally, the billet 7075 T6 upper receiver not only delivers on performance but also offers a more visually striking appearance compared to the conventional A2 style receivers.

But there's more to love beyond just these features...

Includes Radian Raptor SD Charging Handle - The Raptor charging handle is the best on the market for ambi use with large latches for better gripping, and the SD model is built to support suppressor use to eliminate gas blow back

Enhanced Barrel Nut & Handguard Mount - Radian's proprietary handguard mount

Preinstalled SilencerCO ASR Flash Hider - Ready for compatible suppressor

Match Grade 416R 223 Wylde Barrel - Increased accuracy with match grade barrel featuring the 223 Wylde chamber

BRN 180 Gen 2 - Best AR15 Upper With Side Charging Handle

What's unique about this one - The BRN 180 Gen 2 upper distinguishes itself from traditional AR15 uppers through its unique operation inspired by the Armalite® AR-180 from the 1960s. It features a side charging handle and incorporates several improvements from the AR-18/AR-180, including a robust and reliable gas piston operating system.

223 Wylde Chamber - This hybrid chamber is optimized to work with both .223 and 5.56 ammunition. While it bears similarities to a 5.56 chamber, the 223 Wylde chamber offers a tighter freebore size, enhancing accuracy when shooting .223 ammo.

Adjustable Gas System - The adjustable gas system allows users to fine-tune the upper for different types of ammunition and for use with suppressors, ensuring smooth and consistent functioning.

New Handguard Locking System - This innovative locking system ensures that the handguard maintains alignment and rigidity with the upper receiver. Additionally, the new takedown mechanism allows for the removal of the handguard to access the gas system without disassembling internal components.

PWS MK107 MOD 2 Upper

Why this is the best AR upper for a gas piston system - The Primary Weapon System MK107 MOD 2 features the most reliable long stroke piston gas system for a 7" short barrel AR.

223 Wylde Chamber - This hybrid optimized barrel chamber is compatible with both 223 and 5.56 ammunition, offering versatility without compromising performance

3 setting Adjustable Gas Regulator - Users have the flexibility to adjust the gas settings to suit various scenarios, including suppressor use, ensuring smooth and consistent operation.

Preinstalled PWS CQB 556 Muzzle - This muzzle device is specifically designed to redirect sound forward for close-quarters combat, effectively mitigating sound and blast while enhancing overall weapon control.

Upper Receiver Buyer's Guide

You can purchase an complete upper receiver without 4473 background check because it's not a serialized part to be considered as a firearm. 

You can also buy a stripped upper receiver and build it from scratch with parts you want.

There are 4 types of AR-15 upper receivers

• A1 (1960s): It enables accurate firing at up to around 450 yards and provides a 1:12 twist rate. Its flip rear sight is adjustable for windage, and the rear sight has both short- and long-range apertures. It has a light-profile barrel, a fixed-carry handle and forward assist.
• A2 (1980s): Heavier barrel than the A1 model with a fixed-carry handle and forward assist to clear jam.
• A3: The A3 kept all the great upgrades from A1 and A2, now it features detachable carrying handle which enables optic mounts. 
• A4 (Mostly what you see on the market today): Mostly the same as A3, the A4 has M4-style feed ramps that works with existing M4 barrel.

Most AR15 uppers adhere to standard internal specifications, ensuring compatibility with all lower receivers. Many primary upper receivers are machined in the same facilities, leading to a uniformity in quality and design across brands.

The major differentiator in price often comes down to branding and additional quality control. Therefore, it's important not to place excessive emphasis on brand names, as this can lead to overpaying for a product that essentially performs the same function as its less expensive counterparts.

Core Components

The AR15 upper receiver features a couple core components:

• Main upper receiver
• Barrel
• Barrel Nut
• Handguard
• Forward Assist & Associated Retention Pins
• Ejection Port Dust Cover
• Charging Handle
• Gas Block & Associated retention pins
• Gas Tube Or Piston System
• Bolt Carrier Group
• Muzzle Device
• Sights

Importance Of Getting A Good Bolt Carrier Group

The bolt carrier group is the main action component of the AR15 rifle that's responsible for:

• Loading a new round into the chamber
• Fires that round
• Extracts and ejects the spent casing
• Cocks the hammer

NOTE: Some complete upper receiver package includes a BCG and some don't.

It's the main engine of the rifle, and the process repeats and it experiences tons of stress over time. So a good bolt carrier group has the following military specs:

• Chrome lined interior bolt carrier key and bolt carrier
• Coated with a matte black mil-spec finish
• Magnetic Particle Inspected (MPI)
• High Pressure Tested (HPT)
• Bolt carrier machined 8620 steel
• Torqued and staked gas key screws
• Heat treated and shot peened
• Carpenter 158 steel bolt

Mil-spec BCG doesn't mean the BCG is the greatest or the worst. It's simply means the part is made to the military standard.

Gas System

The AR15 has two gas systems:

• Direct Impingement (DI)
• Piston Driven

Picking the right gas system directly impact how the rifle recoils and how it performs when using a suppressor.

The Stoner DI gas tube system is the most common, which involves redirecting the hot gas leaving the barrel back into the gun to recycle the bolt carrier group via the gas tube.

While the direct impingement system can be very reliable, there is no doubt that a lot of fouling can build up on the bolt carrier group.

There are 4 major DI gas system lengths:

• Pistol 4"
• Carbine 7"
• Mid Length 9" - Most reliable & Softer recoil
• Rifle Length 12"

The Piston Driven design uses the propellant gas to operate a rod that acts as an intermediary to exert force on the bolt carrier group to cycle the weapon.

All excess gas is bled out of the gun well forward of the receiver. This helps keep the guns extremely clean. Ultimately it's just like how an AK47 operates.

Barrel Quality & Performance

The majority of complete AR15 upper receivers come equipped with a high-quality 5.56 NATO barrel. This barrel is a critical component that significantly influences the rifle's accuracy, reliability, and overall handling, making it one of the most crucial aspects of the upper.

Many of the AR15 barrels available today are cold hammer-forged and subjected to magnetic particle testing. These processes are carried out to enhance the barrel's service life, accuracy, and durability.

When choosing a barrel, several factors must be considered to strike the right balance between accuracy, weight, handling, parts longevity, and recoil characteristics. These factors include:

• Length - The barrel's length affects both accuracy and handling, with longer barrels typically providing improved accuracy but sacrificing some 
• Profile - The barrel's profile influences weight and heat dissipation. Various profiles offer trade-offs between these factors.
• Material & lining -  The choice of barrel material and lining impacts both durability and accuracy.
• Barrel profile - The profile, or contour, of the barrel can influence weight distribution and heat dissipation.
• Rifling method & twist - The rifling method and twist rate affect the bullet's stability and accuracy.
• Chamber dimensions - The chamber dimensions must match the caliber and type of ammunition being used.
• Gas system - 

Barrel Materials

• 4150 Steel - Used for Mil Spec barrels & Recommend for full auto rapid firing
• 4140 Steel - Uses 10% less carbon than 4150 
• Chrome Molybdenum Vanadium (CMV) - same as 4140 (Most common)
• Stainless Steel - Shorter lifespan

Barrel Lining

There are 2 main types:

• Chrome Lined - It makes the barrel last long and it's the most common in modern AR15 barrels (Most common)
• Ferritic Nitrocarburizing (FNC) - It treats the rifling for better accuracy instead of using coating 

Depend on the legnth of the barrel, generally people will find barrels with these three twist rates:

• 1/8
• 1/9
• 1/7

These twist rates are optimized for specific bullet weights, which is illustrated in the image below:

Barrel Nut & Handguard Locking System

AR15 designs have indeed evolved significantly over time, marked by innovation, strength, and overall improvement. One notable advancement pertains to how the handguard is attached to the receiver, as compared to the older delta ring assembly.

A well-designed barrel nut system plays a crucial role in securely mounting the handguard onto the receiver. This system incorporates an anti-rotational mechanism, effectively preventing the handguard rail from shifting due to factors such as recoil, vibration, rough handling, or heat. This innovation enhances the overall stability and reliability of the firearm.

Or

Another popular type of upper receiver design is the one-piece monolithic upper receiver. In this configuration, the barrel is securely held in place using a proprietary locking system that utilizes locking bolts accessible from the right side of the receiver. This monolithic design provides a high level of stability and precision, contributing to the upper's overall performance and reliability.

Handguard Selection

Picking a good handguard makes the AR stand out from the rest. It's the most obvious part of the rifle that gives the rifle its look and the capability to mount accessories.

In addition, modern AR handguards have improved mounting system on the existing A2 style receiver for providing rock solid handguard installation compared to the delta ring style mount.

The most popular handguard today is the free float system because no part of the handguard makes contact with the barrel, So the force exerted onto the handguard isn't transfered onto the barrel which helps increase accuracy and preserves barrel harmonics.

As far as mounting capabilities go, there are tons of options available, and the 3 most popular ones are:

• M1913
• MLOK
• KeyMod

The two most modular options are MLOK and KeyMod, which give the AR15 a very clean, lightweight and streamlined handguard system that allows the user to mount any accessories as needed without having unwanted weight.

Forward Assist - Yes or No?

The forward assist is an optional component that can be added to the AR15 upper receiver to provide an additional layer of reliability by fully seating the bolt.

While some AR15s do not include a forward assist to save weight and cost, it may be worth considering for those who want the added security of being able to seat the bolt in case it gets stuck while loading a round into the chamber. Keep in mind that the forward assist does come at an additional cost and is not included on all AR15 upper receivers.

Enhanced Charging Handle

A complete upper receiver generally ships with a standard-sized charging handle, and the user can swap out the charging handle at any time.

We recommend a charging handle with a over sized latch with an enlarged surface area for a better grip for shooters wearing gloves and better handling with one hand.

Check out: 3 Best AR15 Charging Handles

Another reason to upgrade the charging handle is to prevent gas blowback while using a suppressed rifle. People generally buy the Precision Flex M84 Gas Buster charging handle for that specific purpose.

Muzzle Device

Most complete upper receivers come with standard birdcage A2 style flash hiders for reducing cost, and they can be swapped out with other types of muzzle devices (More expensive) designed to do the following:

• Compensator - Reduces muzzle movement & dulls perceived recoil
• Flash hider & compensator hybrid - Reduces recoil & hides as much flash as possible
• Muzzle brake - Acts like a compensator, but reduces muzzle rise and recoil impulses significantly
• Pinned & Welded (Not removable)- To fulfill the legal 16" barrel requirement when using a 14.5" barrel

All AR15 barrels have standard 1/2"X28 thread per pitch, and most AR15 muzzle devices will fit.

Flip Up Sights

Many complete upper receivers on the market come with Magpul flip-up front and rear sights, while others do not. It's important to note that these flip-up sights are removable and serve as a backup option in case of optic failure. 

Despite their utility, iron sights are often rarely used as optic reliability and battery life have greatly improved in recent years. Most shooters rely on their optics and use iron sights only to zero in their red dot optics and lasers.

However, offset flip up sights can be advantageous for fast sights transition especially on rifles with magnified optics mounted. For offset aiming, people can use micro red dot sights on offset mounts.

T-Marked vs Non T-Marked

The numbers etched on the upper receiver between every other rail slot rail slot helps the user recall the last position the optic is mounted.

T marks doesn't affect the performance of the rifle at all.

Common FAQ

7075 T6 VS 6061 T6 Aluminum Receiver Comparison

Definitely go with the 7075 T6 for significantly increase durability for the upper receiver. While both receivers work. It's comes down to personal preference.

In fact, 6061 was the original selected aluminum type for making M16s up until 1968 when the military wanted 7075 for added corrosion protection.

6061 and 7075 Aluminum have different properties that make them attractive to manufacturers making products at slightly different price points.

The Difference Between M16 and AR15 BCG

The M16 bolt carrier group is simply an full auto rated AR15 bolt carrier group. Do not let the naming throw you off.

Most AR15 BCG on the market today are all full auto rated, but it will not make a semi auto AR15 go full auto.

For full AR15 build kit minus lower, go here

What Are The Common Upper Receiver Parts That Tend To Wear Out?

Under normal use, the AR15 rifle will last over 20,000 - 30,000 rounds. The upper receiver has parts that are most likely to wear out and require replacement than the lower receiver parts.

• Barrel - Wears out as more rounds are fired
• Gas Block - It can get lose over time
• Handguard deflection - Usually caused by short barrel nut design and poor mounting system
• Bolt - Bolt head & firing pin will experience accelerated wear and tear. In addition, splitting along the cam pin holes or the locking lugs break after excessive use
• Extractor - It can be cracked, chipped, or even break as round counts increase
• Handguard mount - Not necessarily break, but a weak barrel nut system will start to rotate and lose tightness due to vibration and heat

What Does Anti Rotational Handguard Tab Do?

An anti-rotational tab is specifically designed to secure the handguard firmly at the front of the upper receiver. Its primary function is to prevent any unintended rotation of the handguard, which can occur due to factors such as rough handling, recoil, or prolonged exposure to heat over time.

This tab ensures that the handguard remains in a stable and fixed position, enhancing the firearm's overall reliability and performance.

Is Having A Ejection Port Dust Cover Neccessary?

Ejection port cover protects the weapon system especially the bolt area from mud, sand, dirt and other unwanted things that can cause malfunctions.

Close the dust cover when transporting the firearm.