• Reading time:42 mins read
  • Post category:Upper Receivers
  • Post last modified:October 13, 2023
  • Post published:November 21, 2022

🔝 5.56 Upper: The Ultimate Guide

When it comes to firearms, especially the AR-15 platform, the term “5.56 Upper” is frequently thrown around. But what exactly is it? Why would someone want to get a new one? And what are the benefits of using? Let’s dive deep into the world of these uppers, and by the end of this article, you’ll be well-versed in everything there is to know.

Best 5.56 Upper Review

What is 5.56 Upper? 🧐

It refers to the upper receiver of an AR-15 rifle that’s chambered for the 5.56x45mm NATO cartridge. This upper receiver typically includes the barrel, the bolt carrier group, the charging handle, and the handguard. It’s called an “upper” because it’s the top half of the two main pieces that make up the firearm, with the lower receiver being the other half.

Quick Summary

✅ The 5.56 upper is an integral component of many modern rifles, with the AR-15 platform standing out as its most iconic representative. This component is where several critical firearm operations occur, from the firing of the bullet to the ejection of the spent casing.

✅ Designed to accommodate both 5.56 NATO and .223 Remington cartridges, it offers versatility to shooters.

❌ However, while this upper is generally seen as reliable, it’s not without its potential issues. These can range from feeding and ejection problems to challenges with accuracy, often stemming from various factors like maintenance, component wear, or ammunition compatibility.

✅ Regular maintenance, understanding its operation, and being aware of its quirks can ensure smoother performance. For anyone delving into the realm of firearms, especially the AR-15 platform, a comprehensive understanding of the 5.56 upper, its features, and potential challenges is vital.

⭕️ Always prioritize safety and, when faced with uncertainties or persistent issues, seek expert advice.

Top picks of best 5.56 uppers include:

1.🥇 OpticsPlanet Exclusive Daniel Defense Custom Upper Receiver
2.🥈 Aero Precision Rifle Barrel Complete Upper Receiver
3.🥉 Radical Firearms SOCOM Upper Assembly

Why Get a New Upper At All? 🔥

When delving into the world of AR-15s, a common question that arises is: why would someone want to get a new upper? The answer is multifaceted and rooted in the unique design and modularity of the AR-15 platform.

1️⃣ Firstly, one of the most compelling reasons is the ease of caliber conversion. ➡️ The AR-15’s design allows for the upper receiver, which houses the barrel and chamber, to dictate the caliber of the round it fires. While the lower receiver remains consistent, by simply swapping out the upper, a user can transition their firearm to shoot different calibers.

This flexibility means that with a single lower receiver, one can have multiple uppers for various purposes, whether it’s target shooting, hunting, or self-defense.

Best 5.56 Upper

2️⃣ Another reason is the natural wear and tear that firearms undergo. ➡️ Over time and with consistent use, parts of the rifle can wear out. Barrels can erode, and components can become less reliable. Instead of navigating the intricate process of replacing individual components, many find it more straightforward and efficient to replace the entire upper.

This not only ensures that all parts of the upper are new but also provides an opportunity to upgrade to newer models or designs that might offer better performance or features.

3️⃣ Lastly, the allure of customization cannot be understated. ➡️ The AR-15 platform is renowned for its modularity, and this extends prominently to its uppers. A new upper can drastically change the look, feel, and function of the rifle. Whether someone desires a different barrel length, a unique handguard style, or other specific features, the market offers a plethora of options.

This means that every AR-15 owner can tailor their rifle to their exact preferences, making it a truly personalized piece of equipment.

💥 In essence, the reasons to get a new upper are as varied as the AR-15 owners themselves. Whether driven by practical needs, the pursuit of enhanced performance, or personal aesthetics, the decision to invest in a new upper is a testament to the AR-15’s unparalleled adaptability and the passionate community that surrounds it.

Types

When it comes to 5.56 uppers, there are several types to consider:

➡️ Types: 💬 Description:
Standard: This is your typical 16-inch barrel upper, suitable for a variety of tasks.
Pistol/SBR (Short Barrel Rifle): These uppers have barrels shorter than 16 inches. They’re compact and maneuverable but require additional paperwork and tax stamps in the U.S.
DMR (Designated Marksman Rifle): These uppers have longer barrels (18 inches or more) and are designed for precision shooting at longer distances.
Lightweight: As the name suggests, these uppers prioritize weight savings, often featuring pencil barrels and minimalist handguards.
Recon or SPR (Special Purpose Rifle): A hybrid between standard and DMR, these uppers are versatile and can handle both close and long-range engagements.

The world of uppers is vast and varied. Whether you’re a seasoned shooter or a newbie to the AR-15 platform, there’s a 5.56 upper out there that’s perfect for your needs.

Our Top Pick
OpticsPlanet Exclusive Daniel Defense Custom Upper Receiver
The OpticsPlanet Exclusive Daniel Defense Custom Upper Receiver represents an excellent choice for your upcoming AR build. This upper receiver adheres to mil-spec standards, complete with precise indexing marks and M4 feed ramps, and it is expertly CNC machined from high-strength 7075-T6 aluminum. Additionally, it showcases a rugged type III hard coat anodized finish. The barrel, constructed from durable chrome moly vanadium steel, undergoes a cold hammer forging process, resulting in exceptional durability, and features a 1:7 twist rate.
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Benefits 🔥

The 5.56 upper, a staple in the world of firearms, particularly within the AR-15 community, boasts a range of benefits that have solidified its position as a favored choice among enthusiasts and professionals alike.

1️⃣ One of the standout advantages of this upper is its sheer versatility. ➡️ The 5.56 cartridge, around which this upper is designed, is a jack-of-all-trades. It’s adept at handling a myriad of tasks, from casual target shooting sessions at the range to more demanding hunting expeditions or even self-defense scenarios.

Its adaptability ensures that it remains a go-to for many, regardless of their shooting objectives.

Best 5.56 Upper

2️⃣ Another significant benefit lies in the widespread availability of the 5.56 ammunition. ➡️ Given its popularity, manufacturers produce this ammunition en masse, ensuring that it’s not only widely accessible but also often more wallet-friendly than other rifle calibers.

This ease of access and affordability means that shooters can spend more time at the range without breaking the bank.

3️⃣ Accuracy is another feather in the cap of the 5.56 upper. ➡️ Modern manufacturing techniques and advancements in firearm technology have ensured that contemporary uppers are precision instruments. They are capable of producing tight groupings at a variety of distances, making them a favorite among marksmen and those who prioritize accuracy in their shooting endeavors.

4️⃣ Lastly, the modular design of the AR-15 platform, combined with the upper, offers unparalleled compatibility. ➡️ The AR-15’s design ethos is rooted in adaptability, and this extends to its uppers. An upper can be effortlessly swapped out for another caliber or configuration, allowing users to tailor their firearm to specific needs or preferences without the need for an entirely new rifle.

Our Top Pick
Daniel Defense MK18 Complete Upper Receiver
Each upper receiver is meticulously hand-assembled and subjected to rigorous quality assurance testing, guaranteeing the delivery of a superior product. The MK18 package includes essential components such as a bolt carrier group and charging handle, along with a 10.3-inch Cold Hammer Forged Barrel. Additionally, it boasts the renowned RIS II MK18 Rail System, available in both Black and Flat Dark Earth finishes, and is equipped with a Daniel Defense low-profile gas block.
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🥇 Best 5.56 Upper Review

1# Daniel Defense DDM4V7 Complete Upper Receiver

Daniel Defense DDM4V7 Complete Upper Receiver

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The Daniel Defense DDM4V7 Complete Upper Receiver stands out as a solid option for those in search of a dependable upper receiver for their AR-15. It comes equipped with a Cold Hammer Forged 16″ Lightweight profile barrel, which is notably two ounces lighter than the standard V7 barrel. This design caters to those who prefer a less hefty firearm but don’t want to compromise on its efficiency.

The included DD-enhanced Flash Suppressor is designed to minimize flash visibility. Meanwhile, the mid-length gas system promotes consistent cycling and lessens the strain on the components. The MFR 15.0 handguard contributes to weight reduction and offers improved cooling, user comfort, and adaptability.

The upper receiver also boasts M-LOK attachment points across 7 positions and a continuous 1913 Picatinny rail, offering ample space for various attachments like sights and optics. Notably, the Ambi GRIP-N-RIP Charging Handle is adaptable for both left and right-hand users.

Video review

Pros:
  • Cold Hammer Forged 16″ Lightweight profile barrel
  • Improved Flash Suppressor
  • Mid-length gas system
  • Free-floating MFR 15.0 handguard
  • M-LOK attachment points
  • Independent Ambi GRIP-N-RIP Charging Handle
Cons:
  • The Flash Suppressor is not as effective as some other models
  • It may not be ideal for all shooters

 

2# Daniel Defense MK18 Complete Upper Receiver

Daniel Defense MK18 Complete Upper Receiver

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If you’re in search of a dependable, complete upper receiver for your AR15, consider the Daniel Defense MK18. Each upper receiver undergoes meticulous assembly and quality checks to maintain standards.

The MK18 is equipped with a bolt carrier group, charging handle, a 10.3″ Cold Hammer Forged Barrel, a RIS II MK18 Rail System available in Black or Flat Dark Earth, and a Daniel Defense low profile gas block.

Crafted with a Mil-Spec upper receiver and CNC Machined 7075-T6 Aluminum, this upper receiver is designed for durability.

Video review

Pros:
  • High quality
  • Complete upper receiver
  • Hand assembled
  • Quality assurance tested
  • Bolt carrier group and charging handle included
  • 10.3″ Cold Hammer Forged Barrel
  • RIS II MK18 Rail System in Black or Flat Dark Earth
  • Daniel Defense low-profile gas block
Cons:
  • May be too expensive for some
  • Requires a Mil-Spec upper receiver and CNC Machined 7075-T6 Aluminum construction

 

3#  OpticsPlanet Exclusive Daniel Defense Custom Upper Receiver

OpticsPlanet Exclusive Daniel Defense Custom Upper Receiver

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The OpticsPlanet Exclusive Daniel Defense Custom Upper Receiver is a suitable component for AR assembly projects. This upper receiver adheres to mil-spec standards, showcasing indexing marks and M4 feed ramps. It’s crafted from 7075-T6 aluminum using CNC machining and is protected with a type III hard coat anodized finish.

The barrel, constructed from chrome moly vanadium steel, undergoes a cold hammer forging process and offers a 1:7 twist. It possesses a 14.5″ government profile and operates with a mid-length gas system. The gas block, made from 4140 hardened steel, is securely pinned and CNC machined.

The muzzle device is both pinned and welded. Additionally, the bolt carrier group adheres to mil-spec standards, featuring a chrome-lined interior. Accompanying this upper receiver is a Daniel Defense MFR 13.5″ handguard, machined from 6061-T6 aluminum. It provides M-LOK attachment points and is finished with a type III hard coat anodized layer in Milspec+ Cerakote.

Video review

Pros:
  • Indexing marks and M4 feed ramps
  • CNC machined 7075-T6 aluminum
  • Type III hard coat anodized finish
  • Chrome moly vanadium steel barrel
  • Cold hammer forged
  • 1:7 twist
  • 14.5″ Government profile
  • Midlength gas system
  • Low-profile gas block
  • Pinned and welded muzzle device
Cons:
  • Limited style choices
  • The barrel is not chrome-lined

 

4# Aero Precision Rifle Barrel Complete Upper Receiver

Aero Precision Rifle Barrel Complete Upper Receiver

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Crafted from 7075 T6 aluminum and meticulously machined to M4E1 specifications, this upper receiver is designed for longevity. It incorporates M4 feed ramps, a matte black hard coat anodized finish, and laser-engraved T-marks. It also arrives with a pre-installed port door and forward assist.

The handguard mounting platform is integrated into the receiver, ensuring a stable installation. Its 1pc free float design with uniquely shaped rails offers an uninterrupted top rail, suitable for attaching optics and various accessories. This upper receiver is designed to work seamlessly with most low-profile gas blocks and features quick disconnect sling sockets positioned at the 3, 6, and 9 o’clock locations.

The detailed milling on the flats not only enhances grip but also contributes to its aesthetic appeal. Consider this Upper Receiver for a quality enhancement to your AR.

Pros:
  • Machined to M4E1 specs for a perfect fit
  • Forged from 7075 T6 aluminium for strength and durability
  • Matte black hard coat anodized finish with laser engraved T-marks
  • Port door and forward assist installed
  • 1pc free float design with scalloped rails
  • Compatible with most low-profile gas blocks
  • Quick disconnect sling sockets at 3, 6, and 9 o’clock positions
Cons:
  • May not be compatible with all AR builds
  • Some customers have complained about the finish
  • No dust cover or forward assist included

 

5# Aero Precision M4E1 Complete Upper Receiver

Aero Precision M4E1 Complete Upper Receiver

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Made from 7075-T6 aluminum, this receiver is marked with laser-engraved T-marks. It’s equipped with both a port door and forward assist. Notably, its handguard mounting platform is integrated into the receiver’s design.

While the M4E1 is tailored for Aero Precision handguards, it’s also adaptable to most BAR-system handguards. It features anti-rotation tabs, uniquely shaped rails, and an uninterrupted top rail. With an inside diameter of 1.78″, it accommodates most muzzle devices and 1.5″ suppressors.

This receiver is designed to work with low-profile gas blocks and includes a .0785 gas port. Furthermore, it undergoes HP and MPI testing for quality assurance.

Pros:
  • Forged from 7075-T6 aluminum
  • Laser-engraved T-marks
  • Comes with the port door and forward assist installed
  • The handguard mounting platform is forged into the receiver
  • Compatible with Aero Precision handguards, BAR-system handguards, and most muzzle devices
  • Has built-in anti-rotation tabs
  • Scalloped rails
  • Continuous top rail
Cons:
  • Does not fit all handguards
  • Requires special tools for assembly

 

6# Stag Arms AR-15 Stag 15 Tactical Upper Receiver

Stag Arms AR-15 Stag 15 Tactical Upper Receiver

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The Stag Arms AR-15 Stag 15 Tactical Upper Receiver is a dependable and robust component tailored for tactical applications. It comes with a 13.5″ M-LOK handguard, which is lightweight and facilitates the attachment of various accessories. The 16″ barrel, chambered in 5.56x45mm NATO with a 1/7 chrome lining, offers consistent accuracy and dependability.

An A2 birdcage flash hider is integrated to maintain clear visibility during use. Constructed from forged and Mil-Spec 7075 T6 aluminum and featuring a low-profile gas block, this upper receiver is designed for long-term durability.

Video review

Pros:
  • Lightweight
  • Free float handguard
  • 5.56x45mm NATO chamber 16″ 1/7 chrome lined barrel
  • A2 birdcage flash hider
  • Low-profile gas block
  • Forged and Mil-Spec 7075 T6 aluminium construction
Cons:
  • The barrel is not chrome lined which can lead to corrosion over time.
  • The handguard is a polymer and not aluminium which makes it less durable.

 

7# Geissele Usasoc AR15/M4/M16 Upper Receiver Stripped Group

Geissele Usasoc AR15/M4/M16 Upper Receiver Stripped Group

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This Upper Receiver Stripped Group is a notable component for AR-15 enthusiasts. This upper receiver group features a hammer-forged barrel and a mid-length gas system, both contributing to enhanced accuracy and dependability.

It also includes the Super Modular Rail MK 16 handguard, which aids in achieving a clearer sight picture.

Video review

Pros:
  • The hammer-forged barrel provides increased accuracy
  • The mid-length gas system provides reliability
  • Super Modular Rail MK 16 handguard for superior sight picture
Cons:
  • It can be difficult to clean

 

8# Geissele Usasoc AR15 Super Duty Nano Complete Upper Receiver

Geissele Usasoc AR15 Super Duty Nano Complete Upper Receiver

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It’s equipped with features like the Surefire Closed-Tine Flash Hider, Geissele’s Super Modular Rail M-LOK handguard, and an ambidextrous Airborne charging handle. Notably, it incorporates Geissele’s Reliability Enhanced Bolt Carrier Group (BCG), crafted from the durable 8620 carbon steel and designed with extended upper rails for consistent feeding.

The Geissele Usasoc AR15 Super Duty Nano is a dependable choice for those seeking a quality upper receiver.

Pros:
  • Geissele’s Surefire Closed-Tine Flash Hider
  • Geissele’s Super Modular Rail M-LOK handguard
  • Ambidextrous Airborne charging handle
  • Geissele’s Reliability Enhanced Bolt Carrier Group
Cons:
  • Heavy
  • Bulky

 

9# Radical Firearms SOCOM Upper Assembly

Radical Firearms SOCOM Upper Assembly

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Made by Radical Firearms, these AR15 Upper Receivers are designed for straightforward drop-in installation. The RF 16in 5.56mm SOCOM Radical Rail Upper Assembly offers versatility in attachments with its Keymod attachment points on the sides and bottom, complemented by Picatinny rails on the fore-end. This allows for the addition of various accessories like lights, optics, lasers, and bipods.

The assembly kit provides all necessary components for the AR platform upper receiver, excluding the bolt carrier group and charging handle, which can be acquired separately. For those aiming to upgrade their firearm with quality components, the Radical Firearms SOCOM Upper Assembly is a potential option.

Video review

Pros:
  • Made from high-quality materials
  • Easy to install
  • Integrated Keymod attachment points
  • Picatinny rails on fore-end
Cons:
  • May be too difficult to install for some
  • No bolt carrier group or charging handle included

 

10# Radical Firearms Upper Assembly

Radical Firearms Upper Assembly

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The Radical Firearms Upper Assembly 7.5 inch 5.56 M4 Contour is an upper assembly tailored for those involved in competitive shooting. It boasts a slim rail system and a 7.5-inch barrel, both contributing to improved accuracy.

The M4 contouring offers a more ergonomic grip, aiding in better firearm control. An A2 flash hider is integrated to minimize muzzle flash. The assembly is finished in a matte black, giving it a sleek appearance.

If you’re considering an upgrade, this Upper Assembly might be worth a look.

Pros:
  • 7.5-inch barrel for increased precision and accuracy
  • M4 contouring for a comfortable grip and enhanced control
  • A2 flash hider reduces muzzle flash
  • The black matte finish looks great in any setup
Cons:
  • May be too short for some shooters

 

11# Ghost Firearms Elite Complete Upper Receiver

Ghost Firearms Elite Complete Upper Receiver

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This Upper Receiver offers a dependable upper receiver option for AR assemblies. Made to Mil-Spec standards, it’s crafted from 7075 T6 aluminum, ensuring durability without adding excessive weight.

The 4150 steel M4 barrel has a nitride finish, which enhances its performance and provides resistance against corrosion and wear. Additionally, it comes with an M-LOK-free float handguard, which aids in stability and accuracy.

Pros:
  • Machined from 7075 T6 aluminum for superior durability
  • The M4 barrel is nitride-finished for optimum performance and maximum resistance to corrosion and abrasion
  • M-LOK-free float handguard for enhanced stability and precision
Cons:
  • The upper receiver is not compatible with other brands
  • No dust cover or forward assist
  • Limited colour options

 

12# Griffin Armament MK1 RECCE 5.56mm 16 inch Upper

Griffin Armament MK1 RECCE 5.56mm 16 inch Upper

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Designed with precision in mind, this upper aims to improve accuracy and the overall shooting experience for both hobbyists and competitive marksmen. It comes equipped with M-LOK slots, facilitating the attachment of accessories like laser sights or red dot sights.

Additionally, its 1/2×28 industry-standard thread makes it compatible with various devices, including IR laser aimers and night vision tools.

Pros:
  • Ultra-light and low-profile
  • Ultra-rigid upper
  • Enhanced accuracy and shooting experience
  • M-LOK slots for accessories
  • 5R length gas block journal
Cons:
  • May be too light for some shooters

 

13# Griffin Armament MK1 CQB 5.56mm 11.5 inch Upper

Griffin Armament MK1 CQB 5.56mm 11.5 inch Upper

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It comes with an HEDP barrel designed for longevity and versatility, and its construction from nitrided 416R stainless steel ensures durability. The M4 feed ramps and chamber have been refined for efficient feeding, chambering, and extraction.

Additionally, the TRUE-BORE concentric suppressor grade threads are tailored for a seamless fit with silencers.

Pros:
  • Dual-purpose functionality
  • HEDP barrel
  • Nitrided 416R stainless steel construction
  • M4 feed ramps and chamber
  • TRUE-BORE concentric suppressor grade threads
Cons:
  • The Griffin Armament MK1 CQB 5.56mm 11.5 inches Upper is not accurate enough for long-range shooting

 

14# POF USA Complete P-415 Edge Upper Receiver

POF USA Complete P-415 Edge Upper Receiver

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This Upper Receiver is a suitable component for AR-15 assemblies. Made from aircraft-grade aluminium, it has a mil-spec hard coat anodized finish for durability. This upper receiver is designed to work seamlessly with standard AR-15 parts and mil-spec lower receivers.

Video review

Pros:
  • Aircraft-grade aluminum
  • Mil-spec hard coat anodized finish
  • Compatible with all standard AR-15 components
  • Mil-spec lower receivers
Cons:
  • May not be compatible with all standard AR-15 components

 

15# S&W 812011 M&P15 Complete AR-15 Upper

S&W 812011 M&P15 Complete AR-15 Upper

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It features a 14.5″ chrome-lined CMV barrel, extended to 16″ with a permanent Smith Vortex flash hider. The barrel’s right-hand helical flutes are designed to remain secure even during continuous firing, and the fluting increases the barrel’s strength by about 40% due to its added mass.

The upper also includes a Troy 13″ TRX Extreme Handguard, a one-piece, free-floating rail crafted from aircraft aluminium and coated with a MIL-SPEC Type III hard coat complemented by Teflon.

This handguard employs a cutting-edge rotary locking system, ensuring stability and offering versatile mounting options.

So if you’re looking for a complete AR-15 upper that is sure to deliver in terms of both performance and durability, then be sure to check out the S&W 812011 M&P15 Complete AR-15 Upper.

Pros:
  • 14.5″ chrome-lined CMV barrel
  • Permanent Smith Vortex flash hider
  • Right-hand helical flutes on barrel
  • Troy 13″ TRX Extreme Handguard
  • Rotary locking system
Cons:
  • May be too heavy for some
  • The barrel may not be chrome-lined

 

16# ArmaLite M15 11.5in Law Enforcement Carbine Complete Upper Receiver

ArmaLite M15 11.5in Law Enforcement Carbine Complete Upper Receiver

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It has a chrome-lined barrel, enhancing its longevity, and a MIL-STD 1913 rail, facilitating easy sight adjustments. With its 11.5-inch barrel, it’s designed for close-quarters situations.

Additionally, it’s compatible with both 5.56x45mm NATO and .223 Remington cartridges, offering flexibility in ammunition selection.

Pros:
  • Superior durability
  • Rapid and repeatable sight interchange
  • Perfect for close-quarters combat
  • Uses both 5.56x45mm NATO and .223 Remington cartridges
Cons:
  • May be too short for some users
  • The chrome-lined barrel may not be to everyone’s liking

 

17# Colt Mfg LE6920CK Upper Receiver Conversion Kit

Colt Mfg LE6920CK Upper Receiver Conversion Kit

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The Colt Mfg LE6920CK Upper Receiver Conversion Kit offers components for those considering an enhancement to their AR-15 rifle. The kit provides essential parts like a charging handle, bolt carrier group, and backup sight. Its barrels come with a 1/7 right-hand twist, which can contribute to accuracy.

Pros:
  • Highly accurate barrels
  • Converts your AR-15 rifle to the most state-of-the-art configuration
  • Contains everything you need to convert your rifle
  • A great choice for anyone looking to upgrade their rifle
Cons:
  • Requires a high level of expertise
  • The conversion kit may be too complex for some users

 

18# Colt AR-15 LE6960-CCU Upper ReceiverR 5.56 M-LOK

Colt AR-15 LE6960-CCU Upper ReceiverR 5.56 M-LOK

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This receiver mirrors the one found on the Colt LE6960-CCU Carbine and has been shaped based on feedback from seasoned trainers. It incorporates a slim 13″ Centurion Arms M-LOK handguard, a mid-length gas system, and a 16.1″ lightweight profile barrel. The barrel is chrome-lined, has a 1-7 twist rate, and is coated with manganese phosphate to enhance its durability.

Video review

Pros:
  • Top-quality upper receiver
  • Used on Colt LE6960-CCU Carbine
  • Designed with input from experienced trainers
  • Features slim 13″ Centurion Arms M-LOK handguard
  • Mid-length gas system
  • 16.1″ lightweight profile barrel
  • Chrome-lined barrel with 1-7 twist rate
  • Manganese phosphate finish
Cons:
  • Not as durable as some other upper receivers
  • The barrel is lightweight, which could affect the accuracy

 

19# Sons of Liberty Gun Works AR-15 Sage Dynamics Upper Receiver Assembly

Sons of Liberty Gun Works AR-15 Sage Dynamics Upper Receiver Assembly

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Developed in collaboration between Sons of Liberty Gun Works and Aaron Cowan of Sage Dynamics, this upper receiver is well-suited for AR pistols or SBRs and is equipped with various features to enhance its functionality.

The 12.5” barrel, constructed from durable 4150 chrome moly vanadium, has been subjected to high-pressure and magnetic particle testing to verify its performance. It features a carbine-length gas system, a 1-7 twist rate, and a ½-28 threaded muzzle.

Moreover, the 11.5” SOLGW M76 Wedge Lock Rail offers a steady base for mounting optics and other add-ons.

Pros:
  • Expertly crafted
  • Tough 4150 chrome moly vanadium barrel
  • Carbine-length gas system
  • 1-7 rate of twist
  • Muzzle threaded ½-28
  • 11.5” SOLGW M76 Wedge Lock Rail
Cons:
  • Slightly more expensive than other options
  • The barrel might be too short for some shooters’ preferences

Installation 🛠️

Installing a 5.56 upper on an AR-15 is a straightforward process, but it’s essential to follow the steps correctly to ensure safety and proper function. Here’s a step-by-step guide:

➡️ Step: 💬 Description:
Safety First: Before starting, ensure that the firearm is unloaded. Remove the magazine and check the chamber to make sure it’s empty.
Prepare Your Workspace: Lay out a clean, flat surface to work on. Having a mat specifically designed for gun cleaning or assembly can be helpful. Gather necessary tools, such as a set of punches and a hammer.
Remove the Existing Upper (if applicable):
  • Pull the rear takedown pin and the front pivot pin out from the lower receiver.
  • Separate the upper and lower receivers by pulling them apart.
Check the New Upper: Before installation, inspect the new 5.56 upper for any visible defects or damage. Ensure that the bolt carrier group (BCG) and charging handle are in place unless you’re transferring them from another upper.
Install the New Upper:
  • Slide the charging handle into the upper receiver’s charging handle channel, ensuring the wings of the charging handle slide into the notches.
  • Insert the bolt carrier group into the upper receiver, with the bolt facing forward. Slide it into place, ensuring it meshes with the charging handle and moves smoothly.
  • Align the front pivot lugs of the upper receiver with the holes in the lower receiver. Join the two halves together.
  • Push in the front pivot pin and rear takedown pin to secure the two halves.
Function Test: Once the upper is installed, perform a function check. Cycle the charging handle and press the trigger (ensure the firearm is pointed in a safe direction and is not loaded). The hammer should fall. Reset the hammer, put the safety on, and press the trigger again. The hammer should not fall with the safety engaged.
Final Inspection: Before using the firearm, give it a final inspection. Ensure that all components are in their proper places and that there are no loose parts.
Maintenance: After the first time shooting with the new upper, it’s a good idea to clean and inspect the firearm to ensure everything is functioning correctly.

⭕️ Remember, if at any point you feel unsure about the installation process, it’s always a good idea to consult with a professional gunsmith or refer to the manufacturer’s instructions. Safety should always be the top priority.

⬇️ Watch this video to find more information:

FAQ ❓

➡️ Are there different barrel lengths available for 5.56 upper assemblies?

Yes, there are various barrel lengths available for this upper assemblies. The choice of barrel length often depends on the intended use of the firearm, legal restrictions, and personal preference. Here are some common barrel lengths:

➡️ Length: 💬 Description:
Pistol Length (7-10 inches): These are typically used for AR-15 pistols or short-barreled rifles (SBRs). They are compact and maneuverable but may have increased muzzle blast and reduced bullet velocity compared to longer barrels.
Carbine Length (10.5-12.5 inches): Common for short-barreled rifles (SBRs) and some AR-15 pistols. They offer a balance between compactness and performance.
Standard Carbine Length (14.5 inches): This is a common length for military M4 carbines. Some civilian models might have a pinned and welded muzzle device to meet the 16-inch legal requirement for rifles in the U.S.
Rifle Length (16 inches and longer): The 16-inch barrel is the most common length for civilian AR-15 rifles due to U.S. legal restrictions. Longer barrels, such as 18, 20, or even 24 inches, are available and are often used for precision shooting or varmint hunting, as they can provide increased bullet velocity and accuracy potential at longer distances.

It’s essential to be aware of local and federal laws when choosing a barrel length, especially if considering anything under 16 inches, as there may be additional legal requirements or restrictions.

⭕️ Always consult local regulations and consider the intended use and performance trade-offs when selecting a barrel length.

➡️ How to clean the upper?

Cleaning the upper of an AR-15 or similar firearm is crucial for maintaining its performance and longevity. Here’s a step-by-step guide on how to clean the upper. ➡️ Materials Needed:

  • Gun cleaning solvent;
  • Gun oil or lubricant;
  • Bore brush;
  • Cleaning rod;
  • Cleaning patches;
  • Nylon utility brush;
  • Cotton swabs;
  • Microfiber or lint-free cloth.

🟠 First, always ensure the firearm is unloaded before starting. Separate the upper and lower receivers by pushing out the takedown and pivot pins. Once separated, remove the bolt carrier group (BCG) and charging handle from the upper receiver.

🟠 To clean the barrel, apply some cleaning solvent to a bore brush. Attach this brush to a cleaning rod and push it through the barrel from the chamber end to the muzzle several times to effectively scrub the inside. After scrubbing, replace the brush with a patch holder and run solvent-soaked patches through the barrel until they emerge clean. Follow this with a dry patch to remove any lingering solvent, and then with a patch lightly soaked in gun oil to protect the barrel.

🟠 For the chamber, use a specialized chamber brush and solvent to give it a thorough scrub. After scrubbing, wipe the chamber clean.

🟠 When cleaning the bolt carrier group (BCG), begin by disassembling it. This involves removing the firing pin retaining pin, the firing pin itself, the bolt cam pin, and then the bolt. Each part should be cleaned with solvent using a nylon utility brush. The bolt, especially its face and extractor, requires particular attention. Cotton swabs can be handy for cleaning the inside of the bolt carrier. Once all parts are clean, they should be lightly lubricated with gun oil.

🟠 The charging handle, often accumulating carbon, can be cleaned using the nylon brush and solvent. After scrubbing, it should be wiped down and given a light coat of lubricant.

🟠 For the upper receiver, scrub its inside with the nylon brush and solvent. Focus on the chamber area and the inside where the BCG moves. After scrubbing, it should be wiped down to remove any residue.

🟠 After cleaning, the charging handle and BCG can be reinserted into the upper receiver. The upper can then be reattached to the lower receiver. To finish, the exterior of the upper receiver should be wiped down with a microfiber or lint-free cloth to remove any fingerprints or excess oil.

⭕️ Remember, regular cleaning after shooting sessions ensures the firearm’s reliable and safe operation. Always handle firearms with care, store them securely, and keep them away from unauthorized users or children.

⬇️ We believe this video can be helpful for you:

➡️ Can I shoot .223 ammunition through a 5.56 upper?

Yes, you can shoot .223 Remington ammunition through a 5.56x45mm NATO upper. The 5.56 chamber is designed to safely accommodate both 5.56 NATO and .223 Remington cartridges.

However, the reverse is not always true. While the external dimensions of the .223 Remington and 5.56 NATO cartridges are nearly identical, there are differences in chamber pressure and throat length. Shooting 5.56 NATO ammunition in a rifle chambered specifically for .223 Remington can result in higher pressures than the .223 chamber is designed for, which can be unsafe.

⭕️ Always ensure you are using the correct ammunition for your firearm’s chambering and consult the firearm’s manual or manufacturer if you are unsure. Safety should always be the top priority.

➡️ What is the typical weight of a 5.56 upper assembly?

The weight of an upper assembly can vary significantly based on its components, materials, and design features. However, to give a general idea:

➡️ Component: 💬 Description:
Barrel: The weight can vary based on length, profile (e.g., lightweight, government, heavy/bull), and material. For instance, a 16-inch government profile barrel might weigh around 28 ounces (1.75 lbs), while a lightweight profile might weigh less.
Upper Receiver: A stripped standard upper receiver, made of aluminum, typically weighs around 6.5 to 7.5 ounces. When you add components like the forward assist and ejection port cover, the weight can increase slightly.
Handguard: The weight of handguards can vary widely based on length, material, and design. A 12-inch aluminum free-float handguard might weigh in the ballpark of 10 to 14 ounces, but this can vary. Polymer handguards tend to be lighter.
Bolt Carrier Group (BCG): A typical BCG for a 5.56 might weigh around 11 to 11.5 ounces.
Additional Components: Things like muzzle devices, sights, rail attachments, and other accessories will add to the weight.

⭕️ Considering the components mentioned above, a basic 5.56 upper assembly (without optics or additional accessories) might weigh in the ballpark of 3.5 to 4.5 pounds (56 to 72 ounces). However, this is a general estimate, and the actual weight can vary based on the specific components chosen. Always refer to the manufacturer’s specifications for precise weight details.

➡️ What are possible problems with 5.56 upper receiver?

While this upper receiver, especially on platforms like the AR-15, is generally reliable, there are potential issues that users might encounter. Here are some common problems and their potential causes:

➡️ Problem: 💬 Description:
⭕ Short stroking If the gas port or tube is improperly sized or obstructed, the action may short-stroke. This fails to fully cycle the bolt carrier group.
⭕ Failing to extract Buildup in the chamber or worn extractor spring can cause spent cases to stick rather than eject cleanly. Requires cleaning and new spring.
⭕ Feed issues Damaged feed ramps, improper magazines, or buffer/spring problems can impede smooth feeding.
⭕ Accuracy problems A loose or poorly torqued barrel, low-quality barrel, or improper gas system alignment can reduce accuracy.
⭕ Overgassing Too much gas pressure cycles the action violently, accelerating wear. Requires adjusting the gas block if adjustable.

⚠️ Regular maintenance and inspection along with quality components help minimize issues with AR-15 uppers. But malfunctions may still occur given enough rounds fired or abuse.

Conclusion 🏁

In conclusion, the 5.56 upper is a central component of many modern rifles, especially the popular AR-15 platform. It’s where the action happens, from firing the bullet to ejecting the spent casing.

While generally reliable, like any mechanical system, it can have its quirks and issues. Regular maintenance and understanding its workings can help ensure smooth operation.

If you’re diving into the world of firearms, it’s essential to familiarize yourself with the upper, its functions, and potential challenges. ✅ Remember, safety first, and when in doubt, always seek expert advice.

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Charles not a King
Charles not a King
1 month ago

Hey folks, I’ve noticed some surface corrosion starting to develop on the barrel of my 5.56 NATO upper. It’s a bit concerning, and I want to address it before it gets worse. Any advice on preventing and treating corrosion?

    Joshua
    Joshua
    1 month ago

    I’ve had success with using a brass brush and a light abrasive like bronze wool to gently scrub away surface corrosion. Just be cautious not to scratch the finish too much if you care about the aesthetics. Afterward, a thorough cleaning and oiling should help protect against future corrosion.

      Larry
      Larry
      1 month ago

      Prevention is key! After every range trip or exposure to moisture, wipe down your upper with an oiled cloth or patch. Focus on areas prone to corrosion, like the barrel and muzzle. A silicone cloth can be handy for this purpose and leaves a protective film.

        Arthur
        Arthur
        1 month ago

        I’ve been using a 5.56 NATO upper from Armalite on my AR-15 for a while now, and I’m very happy with it. It offers great value for the money. 

          Ethan Smith
          Ethan Smith
          1 month ago

          Hi! What are the differences between a piston-driven and direct impingement 5.56 upper?

            Benjamin
            Benjamin
            1 month ago

            Upgrading to a 5.56 NATO upper is a great idea! I noticed improvements in accuracy and versatility. When it comes to brands, I chose brands like BCM (Bravo Company Manufacturing), Daniel Defense, and Aero Precision. 

              Liam
              Liam
              1 month ago

              Hey everyone, I’m thinking about upgrading my AR-15 with a 5.56 NATO upper. I’ve heard it can improve accuracy and versatility. Your post helped me a lot!