The Case for Buying vs. Building an AR-15 Complete Upper: Making the Right Choice for You

At AR15Discounts, we offer a wide range of parts to help you build the AR of your dreams. So, why do we also sell complete AR-15 uppers? The reason is quite simple: depending on your skillset and tools, building an AR isn’t always the best approach. In this article, we explore why an AR15 complete upper is a solid choice for many and provide an overview of what to consider when making your purchase.

Introduction to AR15 Complete Uppers

For those looking to construct a no-nonsense AR-15 that will work when it counts, purchasing either a complete rifle or a complete upper is often the best route. If a complete AR-15 upper is what is needed, consider the advantages of purchasing from a reputable supplier. Buying direct ensures that all assembly, troubleshooting, and quality control are handled before the firearm reaches the user—all covered by a manufacturer’s warranty and built to industry standards, ensuring reliability.

What is an AR15 Complete Upper?

AR-15 complete uppers come pre-assembled with the essential components needed to complete the upper portion of the rifle, including the barrel, handguard, gas system, and often the bolt carrier group and charging handle. As potential buyers consider purchasing a complete upper, these assemblies fit seamlessly with standard AR-15 lower receivers, allowing for easy customization and upgrades. Opting for a complete upper eliminates the complexities and potential pitfalls of assembling an upper receiver part by part, saving time and ensuring all components function harmoniously.

Build vs. Buy: Considerations

As potential buyers determine whether to build or buy an AR-15, they must honestly assess how much they are prepared to invest in building the gun. While it might seem that money can be saved by purchasing individual parts, the investment isn’t just financial. Time must also be devoted to assembling, troubleshooting, and more.

If the bolt-carrier group isn’t properly staked, does the builder have the tool and knowledge to fix that? Do they know what to look for to tell if the threads on the barrel are done properly? Can they tell if the machining on a lower receiver was done correctly? If assembling things themselves, and they cross-thread a screw or bind a spring and detent, do they know how to fix the issue?

From an expert perspective, the ability of the person building the gun to identify out-of-spec parts when building an AR-15 is becoming more and more crucial. Bad parts can be found from almost every company. The question then becomes who to buy from to lessen the chances of receiving bad parts. Purchasing parts from a company whose primary mission is to build guns correctly rather than focusing on profit first will generally result in a better experience.

In a perfect world, there would be no tolerance stacking or out-of-spec parts, and everyone would have the right set of skills and tools necessary for a successful build, but that just isn’t always the case. When problems arise, it can lead to a lot of frustration. Building an AR-15 should be enjoyable, but when the finished product does not work or is unpredictable, that fun can quickly turn into significant frustration.

Have you ever been to the range, expecting to have a day of fun zeroing your new build, only to have failure after failure for no discernable reason? We have. Quite frankly, it sucks in a way few other things do. We know first hand that a malfunctioning build can also be time-consuming and costly.

The builder might find themselves testing different ammo and magazines, making multiple trips to the range, all without identifying the root cause of the issue. When that point is reached, one option is to box everything up and send it to a professional, ensuring that the problem with the build is resolved. And, no, this is not cheap or fun. Then again, neither is feeling lost and frustrated with no where to turn.

Financially, beyond buying parts, there will also be an investment in tools. The costs and effort can add up quickly, making a pre-assembled upper an appealing and practical choice.

Key Features to Consider

The beauty of the AR-15 is that the configurations available are almost endless. No, it’s not Legos. But, you get the idea. Unfortunately, this wealth of possibilities can also make shopping for a complete upper overwhelming. No worries, let’s break down some main areas of focus to determine the right upper.

Barrel Length and Material:

How long is your barrel and what is it made of? These are probably the most important question as the journey to create the ideal AR begins. AR-15 complete uppers are available in various barrel lengths, typically 16″, 18″, and 20″. As potential buyers consider purchasing a complete upper, they should remember that shorter barrels offer greater maneuverability, while longer barrels enhance accuracy at extended ranges. Stainless steel barrels provide excellent corrosion resistance, whereas chrome-moly barrels are valued for their robustness.

Barrel Construction:

When selecting a barrel, the construction method is. In a recent article with ARBuildJunkie, Alex Hartmann from Ridgeline highlights the benefits of cold hammer forged (CHF) barrels for hard-use ARs that endure high volume, high round counts, and high heat. CHF barrels can take heat better and have greater longevity. Although high-quality button-cut chrome lined barrels exist, the hammer-forging process builds a more durable barrel.

Conversely, match barrels are not designed to withstand high heat and can suffer from throat erosion and gas port erosion, reducing their lifespan. While CHF barrels are less common in the U.S. due to the high cost of the machinery, they are prevalent in Europe and are known for their increased longevity and accuracy. The M24 sniper rifle, used by the Army, featured a cold hammer forged barrel, demonstrating their precision.

Several factors influence accuracy, including barrel quality, chambering, and ammunition. As potential buyers consider purchasing a complete upper, they should know that high-quality barrels with precise rifling and proper chambering enhance shot placement and consistency. For those building their first rifle, a 16″ barrel is a reliable choice.

Gas System:

The gas system is crucial to the AR-15’s operation, with direct impingement and piston systems being the most common. As potential buyers consider purchasing a complete upper, they should note that direct impingement systems are standard and lightweight, while piston systems offer cleaner operation and reliability under adverse conditions. For the most part, we’d stick with the tired and proven direct impingement system unless you’re swimming to the shore with your AR, or low crawling thru sand and or swamp. Even then, a piston operating system isn’t required.

As for what length gas system? If you have no idea where to start, in general, it is advisable to choose a mid-length or carbine system with a barrel length between 14.5 and 16 inches. These systems have a well-established track record and are known to provide excellent velocity and good terminal ballistics with most types of ammunition. It is recommended to select a reputable manufacturer and avoid gimmicky products. We’ll cover that below.

Chambering and Twist Rate:

Popular chamberings include 5.56 NATO and .223 Wylde. As potential buyers consider purchasing a complete upper, the twist rate, indicating how many inches it takes for the rifling to complete one full rotation, affects bullet stabilization. Common twist rates like 1:7, 1:8, and 1:9 suit different bullet weights and applications. You can read some of the basics below.

1:7 Twist Rate
A 1:7 twist rate is popular among target and combat shooters due to its ability to stabilize modern, long-range bullets weighing over 69 grains. It can also handle rounds between 55 and 70 grains effectively. This twist rate is so reliable that it’s used by the U.S. military in rifles such as the M4, HK 416, and M16-A4. Barrels with a 1:7 twist rate are available in lengths from 6 to 24 inches, with shorter barrels suited for close-range combat and longer barrels offering better velocity for long-range shooting. That said, we’d not be shooting 5.56 in anything shorter than a 10.5″, so good luck with your 6″ hand cannon.

1:8 Twist Rate
The 1:8 twist rate is the most versatile among AR-15 twist rates. It provides sufficient stability for bullets weighing between 70 and 90 grains, while also preventing overspin in lighter rounds. Though it performs well with a wide range of ammunition, it delivers the best results with bullets weighing between 60 and 80 grains.

1:9 Twist Rate
A 1:9 twist rate offers a slower spin, ideal for short, lightweight bullets ranging from 40 to 62 grains. While it can handle larger bullets, the slower spin rate may not provide optimal stability and accuracy for heavier projectiles. Unless you have a specific need, we’d steer clear of this.

Speaking of specific needs, there are a ton of other rounds out there, perhaps the most common one being 300 Blackout.

Why Choose 300 Blackout as Chambering

Yes, 300 Blackout is an amazing round, but is it one you should really consider? One of the main reasons to choose 300 Blackout for an AR-15 upper is its versatility. The 300 Blackout cartridge is effective in both supersonic and subsonic applications, making it suitable for a variety of shooting scenarios, from hunting to home defense. 300 Blackout uses the same magazines and bolt carrier group as 5.56 NATO, allowing for easy caliber switching with just a barrel change. The 300 Blackout excels in short-barreled rifles, offering superior performance in close-quarters situations with better terminal ballistics compared to lighter 5.56 NATO rounds.

Suppressor Optimization:

300 Blackout is optimized for use with suppressors, especially when using subsonic ammunition, resulting in reduced noise and muzzle flash.

The trick here is determining if this is right for you. Frankly, if this is your first AR, you’d be better suited with an AR chambered in 5.56. The ammo is a bit cheaper, and overall, it’s a wildly capable round. Do a lot of research to see if you really need what 300 Blackout offers.

Building a 300 BLK Short Barreled Rifle (SBR)

Reputation Matters

If you’re still on the fence about building an upper vs. choosing a complete upper, you need to remember the potential drawback of accidentally buying inferior parts. Companies with solid training, stringent quality control practices, and employees who care about the product will deliver superior products more often than not. These are the brands that AR15Discounts takes pride in carrying. On the other hand, companies focused on quantity over quality may produce parts that fall short due to lack of training, poor quality control, and unreliable warranties. This can leave customers dealing with inconsistent tolerances and frequent part replacements. When you buy a complete upper from a brand you’ve researched and trust, this issues are mitigated.

Durability and Reliability

When it comes to building a rifle for hard use, whether for a professional end-user, a training enthusiast, or someone wanting a reliable rifle for home defense, certain factors become important. If discussing a hard-use AR-15 upper, the advice is clear: everything needs to be mil-spec or better. While there are many parts that exceed mil-spec standards, starting with mil-spec ensures a known quantity, especially when buying from a reputable manufacturer. Durability is crucial, and AR-15 uppers are built to withstand rigorous use. As potential buyers consider purchasing a complete upper, they should note that corrosion-resistant coatings, robust materials, and high-quality manufacturing processes contribute to the longevity and reliability of the upper receiver.

MIL-SPEC – A Misunderstood Standard for Weapon Systems

Conclusion – The Complete Upper Value Proposition

When choosing an AR-15 complete upper, we think that sometimes, the convenience of a pre-assembled upper, combined with the assurance of quality and performance, justifies the price. Potential buyers can have total confidence in the uppers from reputable suppliers. By selecting an AR-15 complete upper from a trusted manufacturer, they get a dependable, high-performing rifle that meets their specific needs, whether for tactical use, competitive shooting, or hunting. If you’re on the fence, you really can’t go wrong with buying a pre-build complete upper and slapping on the lower of your choice. As always, if you have any questions along the way, please don’t hesitate to reach out.