At a Glance: Best AR-15 Upper Parts Kits
Comparison of Best AR-15 Upper Parts Kits
Our Top Pick
|Aero Precision AR15 upper parts kit
|View Latest Price
Our Top Pick
|CMMG AR15/M16 upper small parts kit
|View Latest Price
Our Top Pick
|Rise Armament AR15 upper receiver parts kit
|View Latest Price
Building your own AR15 can be extremely fun and rewarding but it’s not the easiest of tasks. There are many different parts you will need to select as you build your AR15 . AR15 build kits can make the building process much more manageable and hassle-free. These build kits come in many varieties. One kit could contain just a few parts for one section, while another kit could include almost all the parts needed for the entire rifle.
In this article, I’ll cover what components are needed to build the upper receiver, and how upper parts kits can make the assembling process smoother. I’ll also reveal what you need to know to confidently choose the best upper parts kit.
Our guide to the 5 Best AR15 Upper Parts Kits
Knowing which upper parts kit to choose can be confusing. Which kit you buy essentially comes down to what parts you need. To make this clearer, I’ve picked out the 5 best AR15 upper parts kits currently on the market. I’ve tested and reviewed each kit to help you choose which one is right for you.
Aero Precision AR15 upper parts kit
The upper parts kit from Aero Precision includes everything you need to assemble the forward assist and ejection port on your AR15 upper receiver. The kit contains a forward assist assembly with the spring and roll pin. It also includes an ejection port assembly with a cover door, cover spring, and a cover rod with a C-clip.
I found installing these parts onto my upper was straightforward with no issues. The fit and function of all the parts were perfect but in particular, the roll pin felt nicely secure.
All parts are made from high-quality, durable materials designed to withstand wear and tear and last for many years. All the parts are either machined or forged so none of these parts will create a weak spot in your build. Moreover, everything is hard coat anodized and corrosion-resistant.
For the quality it offers, this kit has a very low price tag, making it brilliant value for money. If you’re looking for durable parts without having to spend much, the Aero Precision kit is the best AR15 upper parts kit for you.
- Very affordable price
- High-quality materials
- Durable and long-lasting parts
- Easy to Install
- A top starter kit for first-time builders
- The edges of the forward assist are a bit sharp
- Gives a perfect fit for Aero Precision uppers, but may require some modification for other brands of uppers.
CMMG AR15/M16 upper small parts kit
This CMMG upper small parts kit includes a large range of small parts that you’ll need for your AR15 upper. It includes a selector/ejector spring, extractor spring, takedown pin spring, forward assist spring, ejector, ejector pin, extractor pin, front sight detent, and extractor buffer.
Besides being a great option to build your upper receiver with, this kit also serves as a good replacement parts kit. Many of the components included are AR-15 parts that often need to be replaced so this kit helps you replace all those tiny springs and pins that can easily fly away when trying to install them.
I found the parts gave a perfect fit especially the detent pins which slid in very smoothly. The instructions were clear which made it easy to install all the parts.
Of course, the negative aspect of this kit is that it only includes the small parts, e.g. the pins and springs. If you need a forward assist assembly or dust cover this may not be the best option for you.
This is a dual purpose kit which is amazing value for money. I like how you can use it not only for building an upper but also for refurbishing and repairing one. That being said, because of the missing assembly and cover door, I would be more likely to purchase this as a spares kit.
- Includes all the pins and springs you’ll need
- Serves as a good replacement parts kit
- Gives a perfect fit
- Easy installation
- Great quality, great price
- Only includes the small parts (pins & springs)
Rise Armament AR15 upper receiver parts kit
The Rise Armament kit will help you to build your stripped AR15 lower without any stress or trouble. The kit includes a dust cover with spring, pin, and c-clip, as well as a forward assist with a spring and roll pin.
Rise is renowned for creating high-quality, dependable AR15 parts so you know you’re guaranteed the best with this kit. I found that all the parts installed tightly and securely with no looseness or wobble.
This kit rates high in durability and longevity. What’s more, the top-quality parts are simple to assemble and easy to install. It’s slightly more expensive than other similar kits, but the extra few bucks are completely worth it.
Whether you’re building a new AR15 or wanting to upgrade your current one, this kit could easily be the best AR15 upper parts kit. It will give you much more reliability than your standard kit with an ejector port or forward assist.
- Easy to Install
- Extreme durability and longevity
- From a trusted, dependable industry professional
- All parts secure tightly and securely
DPMS AR15/M16 upper parts kit for free float upper
The free float upper kit from DPMS contains free-float forends that attach to the barrel nut and require no delta ring handguard attachment system. The kit also includes a gas tube, forward assist assembly, ejection port cover assembly, flash hider crush washer, plus pins, springs, and clips.
This kit has all the pieces needed to build a free float upper and they fit well too. The only part that didn’t fit perfectly was the gas tube. It took some tinkering to get it into the gas block. Other than that, I was impressed with the quality.
It’s not the cheapest kit out there but it does have some additional extras that other kits don’t, and it seems like a more ‘complete’ kit. Because of this, I would say it may be the best AR15 upper parts kit for free float uppers.
- Includes a lot of additional extras
- Good quality parts
- Most parts fit well
- A great option for free floats
- The gas tube may be a bit difficult to fit into the block
- Not suitable for non-freefloat uppers
Nemo Omen spare parts kit
Nemo Arms’ exclusive Omen spare parts kit was designed and engineered from the ground up to support the demands of the OMEN 300 Win Mag rifle.
The kit includes a large range of components for your rifle. You will find a firing pin and spring, bolt gas ring plus an extractor with a spring, stiffener, donut, and pin. The kit also contains an ejector with spring and roll pin and even a BCG carrier extension with a spring and roll pins.
The quality of the parts in this comprehensive kit is extremely high. All components are constructed well and offer a lot of reliability. But, this quality does come with a high price tag. This kit is significantly more expensive than the others on the list. Although it’s a great kit for those wanting to splash out, it’s not one for shooters on a budget.
- Comprehensive kit with more parts than standard kits
- High quality and reliable parts
- Designed for the powerful Omen 300 Win Mag rifles
- An expensive option
What is an AR15 upper parts kit?
When building an AR15 you’ll require many different parts for assembling a stripped upper receiver. Because of this, many shooters choose to purchase a kit that includes all these parts instead of selecting them separately.
- An upper parts kit eliminates the hassle of finding every component separately, including hard-to-find pins and springs.
- This makes the building process easier and quicker.
- Once you have your stripped upper, barrel, gas block, flash hider, bolt carrier group, and handguard, you then just need to purchase a complete kit that fits your handguard style and gas system length.
What are the Components of an AR15 upper?
To successfully assemble an AR15 upper receiver there are several parts that you will need. If you’re buying a kit, ensure that it contains all the vital components. If the kit lacks certain vital components that you need, that will leave you searching for them and waiting for shipping, no fun.
Here is a list of parts that you will need to build a high-quality AR15 upper.
Before you can get started you’ll need to acquire a stripped upper receiver. Essentially, a stripped upper is just a solid block of material, usually aluminum, and the foundation of what you will build your upper on. A completed upper will come with the internal parts of an upper kit already installed such as the forward assist button and dust cover.
Upper receivers can be made from various materials, but aluminum is by far the most common material used. Aluminum upper receivers can also be manufactured through a few different methods.
- Forged – Forged uppers provide the ideal grain structure to produce the best mix of mechanical properties like hardness, fatigue limit, and specific weight. However, the downside to forged uppers is that they tend to be denser and heavier. A forged upper is created by “forging” (hammering) the upper into shape.
- Billet – Billet receivers are made by milling a solid block of metal with a CNC machine. This construction method results in slightly less strength than forged, but they are lighter and less dense.
- Cast – Cast metal is the most lightweight but also the weakest. They are made by pouring melted metal into a form (also known as “die casting”).
Along with the stripped upper, a barrel is perhaps the most obvious component that you’ll need. A barrel plays an important role in giving accurate shots every time. More specifically, the barrel twist rate of a rifle will determine the accuracy of the rifle itself. Most twist rates will be about 1:7 for rounds weighing an average of 55 grains and up.
Barrels come in a variety of lengths and are caliber specific, meaning you’ll need to use the right one for the caliber you shoot. Barrels also come in different materials. The two primary materials you’ll find are stainless steel and chrome-moly vanadium (CMV).
- CMV requires some care but it can last longer.
- Stainless steel barrels will not corrode, but won’t last as long as CMV.
Another component that is crucial for shooting accurately is a handguard. The handguard slides over the barrel and attaches to the upper receiver. It protects your hand from the heat of the barrel when shooting.
A handguard rail system will allow you to fully customize your rifle and accommodate all kinds of accessories that will help give you a more accurate and precise shot. There are different types of rails you can choose from such as an M-LOK or Picatinny which offer easy mounting for scopes and optics as well as many other important accessories.
Bolt Carrier Group (BCG)
The bolt carrier group (BCG) is the heart of the AR15. It consists of several critical components including the bolt and firing pin. The bolt in a BCG is caliber specific so you’ll need to check that the kit your buying has the appropriate one that you need.
BCGs are typically available in 3 finishes: nickel boron, black nitride, and phosphate.
- Phosphate is the standard bolt carrier group finish that has been the industry standard for many years.
- Nickel boron is an easier to clean option. It also generates less friction than phosphate and gives a silver color.
- Black nitride has the same benefits as nickel boron but gives a black finish instead of silver.
The charging handle is used to manually charge the action of the rifle. Charging handles are available in a standard configuration, with a single lever on the left side, as well as ambidextrous configurations that have activation levers on both sides.
The forward assist is a button that’s usually placed near the bolt closure. When you hit the forward assist, the bolt carrier is pushed forward, ensuring that your round is properly seated.
Although not part of the original M16/AR-15 design, a forward assist is an important element on an upper receiver. If powder residue or other matter prevents the bolt from going completely into the battery, the forward assist can help force the round into the chamber and the bolt into its firing position.
A dust cover is not a vital element of an upper receiver but it is a clever addition. When closed, a dust cover keeps dirt, dust, and other debris from fouling your weapon. Once fired, it opens so that the expended shell can eject from the ejection port.
Pins, springs, etc
Of course, for any firearm construction, you will need pins, springs, clips, and nuts to assemble all the parts. Upper parts kits usually provide the right amount of these small but vital pieces.
Are all AR15 upper parts kits the same?
The main difference you will find in upper parts kits is what’s included. Some kits will include parts like a handguard, however, most will just contain a forward assist, ejection port, and the appropriate Springs, Pins, etc. Furthermore, the quality of the parts can differ among upper parts kits too.
How to choose the best AR15 upper parts kit
Before you purchase your upper parts kit you should consider the following three factors.
I would recommend that you check exactly what your kit includes so that you don’t begin assembling your upper to then notice that something is missing. On the other hand, if you find your kit has a part that you don’t need, you can just keep it as a spare in case of a malfunction. It’s always good to have extras laying around.
- The majority of kits will include all the basic parts. These include all the forward assist and ejection port components along with the necessary pins, springs, and clips.
- Some more complete kits will include additional items such as a gas tube or bolt gas ring.
As with all AR15 customization products, prices can range drastically from cheap to expensive. The good news is that if you’re on a budget there are many affordable upper parts kits available. If you’re opting for a budget kit just be sure that all the parts included are high in quality.
Sometimes a low price tag does mean low-quality parts that can easily break. Because of this, spending a few more bucks can make a big difference. Try to find the right balance between affordability and quality.
The United States has a reputation for creating high-quality AR15 rifles, parts, and accessories. Because of this, many rifle shooters, myself included, prefer to stick with American-made AR15 products.
More specifically, most gun manufacturers in the United States have strict standards and rules on how they make upper receiver parts. Therefore, if you buy from a well-known, trusted American manufacturer, you’ll have the confidence and assurance that you’re receiving supreme quality parts.
- Each component in an upper receiver parts kit requires specific mechanical properties, so it should be made of a certain minimum grade of a certain material
- We can’t go into every specification for each component here, but we can advise you to go with a manufacturer that is forthright about what materials they use and why. This is usually an opportunity for a manufacturer to brag and market their parts kits as superior.
- If the manufacturer’s approach is ‘no comment’ or ‘it’s all mil-spec,’ assuming it’s a well-known brand, if the price is right, the kit should still be a solid budget option.
Tools you will need to build your AR15
Along with the components in your kit, here is a list of essential gunsmithing tools you might need to build your AR15 rifle.
- Workbench – A good workbench will help manage and store parts in an organized way as you go through the AR15 building process. It will also give you a sturdy surface to mount your bench vise to.
- Bench vise – A bench vise allows you to easily manipulate and install tiny parts. It also lets you mount your vise block and it securely holds your upper and lower receivers in place when torquing down your barrel and castle nuts.
- Vise block – Vise blocks are specifically made to hold your upper and lower receivers firmly in place when installing your parts. This prevents crushing, marking, or scratching your finish.
- Pin punches – Roll pin punches feature a balled tip that centers the roll pin when you drive them in. This also prevents the pins from malfunctioning or crushing.
- Pin holder – Pin holders aren’t necessary tools but they’re very useful to have. This helpful holder will hold your roll pin in place and align it properly.
- Armorer’s wrench – A good armorer’s wrench will make your AR15 build much easier! These wrenches allow you to do many things like installing barrel nuts, castle nuts, receiver extensions, and flash hiders.
- Torque wrench – Certain components, such as barrel and castle nuts, have very specific torque specifications that require an accurate ½ inch drive torque wrench to get right.
- Hammer – Hammers are great for stubborn roll pins or stuck parts. A 4 or 8-ounce hammer should be sufficient in most cases.
- Pliers – Needle nose pliers are a brilliant tool for manipulating and holding tiny parts. They help push in detents and install your magazine release too.
- Screwdrivers – Screwdrivers are also useful for pushing down springs or detents.
Summary – What is the best AR-15 upper parts kit?
The kit that’s best for you comes down to your personal needs and will depend on which parts you require. In terms of quality and price, I feel the best AR15 upper parts kit is the Rise Armament AR15 upper receiver parts kit.
I hope this guide has given you a deeper understanding of the role an upper parts kit can play in assembling your rifle. Building an AR15 does not need to be daunting. By breaking down the process into one section at a time, and using these kits to help you out, it can be an enjoyable and satisfying experience.