There is nothing wrong with buying a fully built AR-15 from a gun store or sporting goods store.
However, the process of building one from parts or a kit can be extremely rewarding. It helps the builder to better understand the function of their rifle and offers a sense of accomplishment and pride.
Thankfully, there are plenty of great AR-15 kits available that make it easy for even a beginner to successfully build a rifle. Take a look at the best AR-15 build kits available today below.
Comparison of the Best AR-15 Build Kits
| IMAGE | PRODUCT | |
|---|---|---|
Our Top Pick  |
| View Latest Price โ |
 |
| View Latest Price โ |
 |
| View Latest Price โ |
What to Watch For When Building an AR-15 From a Kit
There are a few important things to know and to look out for when shopping for an AR-15 build kit. It might be overwhelming at the beginning, but a little knowledge will help you feel more informed and confident in your decision.
This Section Written By:
Brian Belko
Expert Author
Brian is an experienced freelance writer and technical writer who has previously written for publications such as Wide Open Spaces, Bigfoot Gun Belts, Alien Gear Holsters, and Kampgrounds of America. He brings both a passion for writing and a love of the outdoors to his published content.
Aside from writing and the outdoors, Brian enjoys gardening, being a co-host on The Nostalgia Blast Podcast, and learning to code.
Not as Hard as You Think
If you have never built an AR-15 before, try not to be intimidated by the idea of doing so. Building an AR-15 from a built kit is not as hard as it may sound and it does not require any special tools to accomplish. That doesnโt mean that there wonโt be moments of frustration during your first build. While most components are secured using pins, there are a few springs that need to be positioned correctly and this can sometimes take a few tries.
The key is to understand this going in. Doing so will help you to avoid getting overly frustrated. If you do find yourself feeling that way during a build, it is best to step away for a few minutes and take some deep breaths. Youโll usually find that parts go exactly where you need them to once you do.
Photo credit: blackrifledepot.com
Why Get a Kit?
It is entirely possible to purchase each individual part of an AR-15 separately. If complete customization is important to you, this might be the way you want to go. However, there is nothing wrong with opting for a build kit. In fact, build kits have a lot of advantages. One of the main advantages is the confidence in knowing that all the parts in a kit go together. Another advantage of a kit is having a company to turn to in case something is missing or doesnโt seem to be right. There is also the advantage of saving a little money as build kits tend to be more affordable.
AR-15 build kits are designed to make gun building easy, rewarding, and satisfying. They hit an excellent middle ground between an off-the-shelf, pre-built rifle and a fully custom rifle bought piece by piece.
Checking Parts Lists
Donโt let the name fool you. Build kits do not necessarily include every single part of an AR-15 rifle. It is always important to look closely at what is included so you know exactly what you are getting and exactly what other parts you will need to buy. Not only does this help with planning, but it also helps prevent going over budget if you have an upper limit on how much you want to spend.
Review of the Best AR-15 Build Kits
The following is a list of the six best AR-15 build kits currently on the market. As you look through each one, you should note the features and characteristics so you know which parts are included in a certain kit. Your job is to find the best kit you can find that contains all the parts you need.
Each one varies as to what it includes, so be sure to check closely into the kit you are considering. Letโs take a look at the first AR-15 build kit on our list:
Best Overall:
CMMG AR-15 Lower Gunbuilder's Parts Kit
Pros
Cons
What Recent Buyers Report
New buyers were pretty happy with the build kit. They were able to fit this on most stripped lower receivers. One user said he had all the parts he needed to make his AR-15 build fully functional and ready to go once the building project was complete. He also added that he would get a kit like this again for future AR-15 builds.
Why it Stands Out to Us
This kit has all the parts to make a lower receiver function. This includes the firing group and the trigger group. They are important to the AR-15 rifle. Because without them, the rifle will obviously be rendered useless. Each part is made from high-quality materials and is guaranteed to last you quite a while. So if you want high-quality, fully functioning parts right out of the box, this kit will never disappoint you.
This kit from CMMG is specifically aimed towards building the lower of your AR-15 rifle. The lower parts kit includes a takedown pin, pin detent and spring (2 each), hammer, trigger pin (2), safety selector, magazine catch and release, bolt catch and plunger, buffer retainer, and all the other required pins and springs. In short, this lower parts kit is a all-in-one solution for building your lower receiver.
The kit is helpful for building a customized lower, especially with a custom grip and trigger group. The finish of all the parts in this kit is very consistent and the parts have been machined to fit well. Every component in the package is separately packed and clearly labeled so you can keep things organized during installation.
All parts of the kit have a matte black finish so they blend really well with the aesthetics of your rifle. All the parts in the kit are mil-spec and compatible with all lowers, so you donโt have to worry about selecting a specific type for your lower. Finally, the kit has been priced so well, you may end up buying an extra as a backup.
Who Would Use This Most?
This kit will certainly be a must-use for those building their AR-15 rifles from scratch. In fact, this should be one of the first build kits you should get. Thatโs because a lower receiver kit will contain some of the most vital parts of an AR-15. Itโs a must-have if you need something like a good trigger or firing assembly.
Bottom Line
The CMMG AR-15 Lower Gunbuilding Lower Parts Kit will certainly stand out as a must-have kit for the AR-15 builder. If you want something that will give you long-lasting parts that will function as a unit once you install each and every one, this build kit should be high at the top your list of must-haves.
The Lower Parts Kit from CMMG is an inexpensive and complete solution to build your AR-15. The kit is compatible with all lowers, which is another attractive feature. This means you can also keep one as a backup for replacing worn out parts.
Runner-up:
Geissele Automatics LLC - AR-15 Lower Parts Kit
Pros
Cons
What Recent Buyers Report
New buyers were able to fit these parts on their lower receivers without any issues or permanent alterations to their rifles. While a majority of them have used this as part of their AR-15 building project, others have used this as an upgrade kit to better improve their lower receiver. Overall, the parts function properly and everything was smooth and put together.
Why it Stands Out to Us
This kit contains all your small parts, like your pins and springs. These include parts like your buffer tube, trigger assembly, and your safety assembly among other parts that are essential to your AR-15 lower receiver. This is a kit that has all the parts to last you years or even decades. So long as you take great care of your rifle, there is no question of how long your newly built or upgraded AR-15 will last.
The Geissele AR-15 Lower Part Set assumes that more-experienced builders usually upgrade their grips and triggers first. In that context, Geissele LPK includes all parts except the fire control group and pistol grip.
Unlike some kits that offer Metal Injection Molded (MIM) parts, these quality AR-15 lower components are made from hardened stainless steel or by casting process that meets or exceeds military specifications (Mil-Spec).
The Geissele AR-15 Lower Parts Kit consists of the bolt catch, bolt catch plunger, spring and roll pin, mag release, mag release button and spring, buffer retainer and spring, safety, safety detent and spring, trigger guard and roll pin, takedown detents and springs, and pivot and takedown pins.
With 17 parts, this slightly-expanded basic set is an extremely customizable AR-15 gun build kit. It only provides what you need without the extra parts you're going to replace anyway.
Who Will Use This Most
If youโre either a builder or looking for a great upgrade kit, this will probably be something thatโs right up your alley. No matter what you use the kit for, youโll have a lower receiver that has fully functioning parts that will work like a well-oiled machine. Youโll be firing off your shots a lot smoother than before (assuming youโre upgrading).
Bottom Line
The Geissele Automatics LLC AR-15 Lower Parts Kit might be what you need if youโre looking to add on the lower receiver to your AR-15 build or if youโre simply in need of a full-on upgrade. Once you add these parts, your AR-15 rifle will feel like itโs fresh off the assembly line and will function like itโs a brand new rifle.
Best for the Money:
Brownell's Lower Completion Kit
Pros
Cons
What Recent Buyers Report
A lot of new buyers were in search of a build kit for their lower receivers. Most were using this simply for building one from scratch. Meanwhile, a good chunk of the new users were in search of a lower kit for the purpose of upgrading. All the parts were easy to install and function properly, as advertised.
Why it Stands Out to Us
Once again, youโre looking at a lower parts kit that will have all the parts you need to ensure that your lower receiver is fully functional. Also included is a lightweight buttstock you can add onto your rifle. This will allow for reduced recoil and will give you better control over your rifle. If you need a few good, high-quality parts to ensure your rifle is in tip-top shape after an upgrade or a complete build, this kit might be right up your alley.
This lower receiver completion kit from Brownells contains all the parts of the lower receiver assembly youโll ever need. The kit includes all the pins, springs, buffers, and other components for completing the lower receiver, along with a trigger assembly.
In addition to that, the kit also includes a six-position adjustable stock for your AR-15. The stock has been manufactured from nylon-based polymer and reinforced with fiberglass to deliver strength and durability to the structure.
All the components of the kit are mil-spec and compatible with all AR-15 lowers. The buffer tube in the kit has been properly machined to match the stock interior diameter for a snug finish. The kit and stock are packed in separate pouches with proper markings to allow for easy installation. This is one of the only kits on the market which comes complete with a buffer tube and a stock.
Additionally, the inclusion of the buffer tube and stock in the kit make it more economical and saves you a lot of money, which would otherwise be spent on buying a separate stock. The parts in the completion kit fit snugly and offer good value for the money.
Who Will Use This Most
If you need a few good upgrades, this kit will definitely give you some of the parts you need to make it a successful one. Likewise, if youโre simply building a rifle from scratch and all you need are the best functioning parts for the lower half of your AR-15, this kit is something you should consider investing in.
Bottom Line
The Brownells AR-15 Lower Receiver Kit might be the best one to invest in if youโre looking for parts that are the closest to factory replacements. All your lower receiver parts are included and ready to be installed. Donโt be surprised that they work just as smoothly or better than your previous lower receiver parts.
The complete lower parts kit from Brownells includes the buffer and an adjustable stock in the package, which is definitely a plus. Considering its overall price, it is a good bargain with the inclusion of those extra items. Plus, it is compatible with all AR platforms.
4. Brownells' Tactical Upper Build Kit
Pros
Cons
What Recent Buyers Report
Most new users purchased this as part of their building project. But as expected, not a lot of other users needed an upper receiver kit for upgrading purposes. One user said he managed to add on his upper receiver with the parts included in a matter of minutes. He was impressed with the inclusion of the top rail since it allowed for additional customization for scopes and optics.
Why it Stands Out to Us
This upper kit doesnโt give you a lot but what it does give you are vital parts for your rifleโs upper receiver. The top rail is what youโll need for the purpose of installing your favorite scope or sight. Letโs face it, accuracy is important and you want to make the most of it with your rifle. Letโs not forget the ejection port assembly that will allow for unobstructed discarding of brass once you fire off each and every shot.
Here comes a quality upper receiver assembly kit for your AR-15. The kit includes one stripped upper receiver forged from 7075 T6 aluminum with M4-type feed cuts on the inside for reliable feeding. The receiver includes a forward assist assembly and an ejection port assembly along with the assist push-pin and the ejection port cover.
The assembly build kit is compatible with standard and mil-spec lowers and components. For your knowledge, the kit has an aero-precision upper receiver with a precise finish and features compatibility with all lower receivers.
The flat-top upper has rails on the top to let you mount optics with ease. The upper is aesthetically pleasing and the presence of a forward assist also helps with the overall operation of your AR-15, preventing jams and cycling issues.
The upper is easy to install and offers good value for the money. Additionally, the proper head spacing for the BCG is also an added advantage. The charging handle is mounted on the rear, so take note of that before buying.
Who Will Use This Most
If you need some essential parts that will fit your upper receiver, obviously this is the kit for you. Especially when you need to add on your favorite scope or optic for that accuracy boost for your rifle. Whether itโs built from scratch or in need of an upgrade, your AR-15 will have a well-deserved upgrade once you tack on this upper receiver kit.
Bottom Line
The Brownells AR-15 Tactical Upper Assembly Build Kit is the closest you can get to possibly finding the best factory replacement parts for an upper receiver. This kit contains all you'll ever need in an upper receiver build or upgrade. Why settle for less than high-quality when you can get it all in a kit like this?
The AR-15 upper from Brownells is an economical, high-quality, and complete solution for building your rifle. It fits all AR lowers and has a flat-top with rails. Plus, donโt forget the eye-catching aesthetics.
5. DPMS AR-15 5.56 16" Oracle Rifle Kit
Pros
Cons
What Recent Buyers Report
A lot of new buyers were pretty impressed with the kit. They were quick to point out that this contained so many needed parts for their AR-15 building project. One user said he was able to use every part to his advantage and was able to knock out a huge majority of his building project with this kit alone. He added that the top rail in the kit actually fit his favorite AR-15 rifle scope.
Why it Stands Out to Us
This kit pretty much has it all, parts for your lower receiver, upper receiver, and everything in-between. So this kit pretty much gives you what you need in order for the building project to go quite smoothly. Every single part is made from the highest quality materials. For example, the pistol grip is made from polymer, which is designed to give you excellent grip and control over your rifle in even the most adverse weather conditions.
Recently, DPMS released its well-planned AR-15 build kit chambered in 5.56 NATO. It is intended for both first-time buyers and more experienced shooters.
The Oracle kit includes everything except a stripped lower receiver, sights, and a magazine. The A3-type, flat-top upper receiver built from 7075 T6 aluminum comes with the ejection port cover and is forward-assist installed. The upper includes Glacier Guard handguards, which are generally regarded as sufficiently heat-resistant. It also includes a standard BCG and charging handle assembled at the factory.
This affordable kit features a 16โ Lite-contour barrel made of 4140 chrome moly steel and is topped with an A2-style flash hider. The light "pencil profile" barrel has a 1:9 rifling twist rate. M4 feed ramps ensure reliable feeding of both commercial and surplus ammunition. The unit has a carbine-length gas system with a single-rail Picatinny rail gas block.
The Oracle Rifle Kit sports a proprietary Pardus collapsible buttstock assembly with a commercial diameter buffer tube, carbine buffer, and all necessary components to complete the construction of this introductory carbine.
Who Will Use This Most
This will definitely be a kit worth using by most amateur AR-15 builders. In fact, this would be a great build kit for the first time builder. Since you pretty much have all the parts there, it saves them a lot of time trying to figure out which parts they need in order to make the build complete. If you want a build kit that has all the basic parts you need and then some, youโd be hard-pressed to find a kit like this anywhere else.
Bottom Line
The DPMS Kit has every single part that is vital to the AR-15's functionality. Be sure to add on each part little by little as you go along. By the time youโre finished, youโll have an AR-15 that is ready for a few test fires at the range. Once you get some successful shots off, then itโs off on the next hunting or target shooting adventure.
6. Bushmaster Firearms AR-15 Lower Parts Kit
Pros
Cons
What Recent Buyers Report
As expected, a lot of new users were pretty impressed with what was included in the build kit. They installed every single part without a single issue each within a few minute's time. The parts were able to fit most lower receivers without issue.
Why it Stands Out to Us
All your large and small parts are included in one package. Thatโs probably what you need in a lower receiver kit, anyway. Not only that, each one is ready to install and able to do what itโs supposed to do. Youโll have a fully assembled trigger and firing assembly ready to go once you're able to put it all together. One of the best parts, of course, is the pistol grip. Made from high-quality polymer, it allows for a superior grip in any weather conditions. So if itโs nice and dry or raining cats and dogs, you have a good handle on your rifle.
Bushmaster Firearms has earned its reputation and popularity by manufacturing AR-15 style rifles. They also offer highly-regarded and affordable kits for this legendary rifle.
The Bushmaster AR-15 lower parts kit offers a carefully-selected assortment of parts with everything you need to finish your build.
However, the kit doesn't include the lower, the buffer tube, buffer, or buffer spring. The Bushmaster lower parts kit consists of an injection-molded pistol grip - a classic A2-style grip and same type of high-density polymer trigger guard. The set comes with a single-stage trigger featuring typical military or tactical rifle heavy trigger pull.
The rest of the internal parts are based on mil-spec allowing you to complete or refurbish a stripped AR-15/M16 receiver. This set of components has a uniform surface treatment with an average finish and quality.
Who Will Use This Most
This would make a perfect lower receiver kit simply for building purposes. This may not be suitable for upgrades, since youโll have so many parts to work with on this kit alone. So if youโre in the process of building an AR-15 rifle or are about to do so, youโd be insane to pass up the opportunity to give this kit a closer look.
Bottom Line
The Bushmaster Firearms LLC AR-15 Lower Parts Kit has everything a builder wants to build out an entire AR-15 lower receiver. Once you build out every part, youโll have a lower that will work smoothly and provide reliable firing power like no other.
7. Brownells' AR-15 Receiver Set w/Lower Parts Kit & Stock
This 5.56x45mm AR-15 receiver set with a lower parts kit and stock is made exclusively for Brownells and consists of field-proven components. The complete upper receiver comes with an M4-profile 16โ barrel featuring carbine-length gas system and an A2 flash hider.
The common A3 flat-top upper receiver is machined from forged 7075 T6 aluminum. It has 10โ polymer handguards and a KeyMod rail system. The upper receiver set comes with the ejection port cover assembly and forward assist installed. The kit also includes a standard MPI-tested bolt carrier group and charging handle made of 6061-T6 billet aluminum.
A mil-spec M4-style carbine adjustable stock completes this set. The whole stock assembly is a mixture of aluminum and fiberglass-reinforced nylon. It is extremely resistant to impact. The most intricate part of this set is an 80-percent Anderson lower receiver. Of course, this calls for more-advanced armory-level gunsmithing. The mil-spec Anderson LPK (lower parts kit) includes the trigger with a hammer, a pistol grip (A2-style), and all other internals.
Some Assembly Required
Building an AR-15 is actually not too difficult. The hardest part is usually trying to get the tiny springs into place without them bouncing all around the garage. Not a lot of tools are needed and most pieces are simply attached with pins. For a true enthusiast, building from a kit is a fun way to take the next step in the field.
Letโs have a look at some of the pieces involved. A build kit may include some or all of these and even more depending on the type of kit and the manufacturer. Looking at these factors will help you understand whether itโs the right kit for you. If not, youโll want to make substitutions or just buy each piece individually.
How to Choose an AR-15 Build Kit
Building an AR-15 from scratch can be a challenge. It will also take a certain build kit to make sure the project is complete from start to finish.
Instead of shelling out money for individual components from various brands, you can buy a build kit for a lot less, saving time and effort in tracking down the individual parts instead of buying them separately.
Buying a build kit doesnโt allow the same level of customization as buying every individual part separately, but it allows you to experience the thrill of building your own AR-15. It also allows more customization than youโd get just buying a rifle off the shelf, so it kind of falls into a nice middle ground.
Not every kit is created equal. Here are a few things to look for while selecting a build kit of your choice:
Price
You can find a build kit that is affordable for your budget in terms of quality and performance. Itโs important that you find the best you can afford, rather than try to save a few dollars and sacrifice quality in the process. Whether youโre on a budget or have money to play around with, youโre bound to find a build kit youโll enjoy using.
Does it Have All the Parts You Need?
Not every AR-15 build kit will have all the parts you need to completely build out a rifle, so itโs important to know which parts are available when you receive the kit. Having as many parts as possible will lessen the amount of time your project will take. It will also allow you to save time and money trying to track down all the other parts you need individually.
Ease of Installation
If you lack gunsmithing skills, know that youโre not alone in this regard. These build kits will ensure that your build will be easy from start to finish. Every part that youโll have handy will be easy to install and will not require a ridiculous amount of gunsmithing skills. Find a kit that includes parts that are easy to install piece-by-piece.
The Pieces Youโll Need to Put Together
The main parts of the AR-15 are related to the accuracy and reliability of your gun.
Photo credit: sofrep.com
The more comfortable you are with your gun, the better you will shoot with it and the more accurate it will be as a result. Being especially mindful of some of these pieces will help you build a more reliable gun.
Upper and Lower Receivers
The upper receiver or lower receiver of an AR are the central pieces of your rifle and are the keys to the ARโs modular system. Most receivers will work on any AR but buying an upper/lower pair from the same company will typically eliminate any issues in fit and finish.
Receivers come in various finishes and looks, but popular options are polymer and aluminum. You should choose a high-quality build material to ensure your weapon will take any punishment that will occur as a result of normal use. Forged lower receivers are the most common type of lower receiver on the market, while billet receivers are less common and more expensive.
Grip
The way you hold your gun while shooting can make or break your shot. Because the grip is your personal connection to the rifle, it should feel natural in your hand, as if itโs an extension of your arm. Any discomfort you feel from the grip, whether due to protrusions, sharp edges, or the wrong size, will impact your shooting.
If your hand is large, consider changing the stock grip for a larger one that feels like it was made for you. A number of great grips are available and you can choose the grip that feels just right for you.
The typical grip for an AR-15 is the pistol grip, but in some states like California, they are prohibited. Featureless grips can help you satisfy the legal requirements in those states.
Photo credit: thril.com
Handguard
By getting a new handguard, you not only improve the rifleโs aesthetics, but also the comfort, accuracy, and versatility of mounting accessories. The handguards come in various types, such as free-float or drop-in, and with or without rails. They can be made from a variety of materials.
Free-floating handguards not only look good, but they offer slight increases in accuracy over traditional two-piece, drop-in designs. Free-floating handguards also offer plenty of space to attach accessories via their MIL-STD-1913 rails. If youโre planning to use the AR-15 for hunting, for example, youโll appreciate the ability to add a night vision device, extra optics, and a holographic sight.
On the other hand, drop-in handguards are much easier to install or swap out.
The most common handguard lengths are rifle, mid-length, carbine and pistol. Generally, you should match your handguard to your gas system length, but you may be able to fit a longer handguard on a shorter gas system if you use a low-profile gas block.
Photo credit: at3tactical.com
Barrel
The barrel affects the weight and overall performance of your rifle. A lined barrel such as chrome, Melonite, or Nitride coatings will add to the life of the barrel, extending it by over 5000 rounds fired.
Even for the more expensive ARs, over time, the accuracy of a barrel can decrease as a result of thousands of shots. The AR-15โs barrel has a lifespan of between 10,000 and 20,000 rounds, after which most show a serious loss of accuracy.
How to Build an AR-15
An AR-15 is among the simplest of rifles to assemble. Building an AR-15 doesnโt require a lot of expertise or complicated tools. If you are a bit familiar with disassembling or servicing a firearm, it will not take more than ten minutes to build an AR-15. The rifle is mainly comprised of two parts, the upper receiver and the lower receiver. All other components just fit into these two.
The best procedure is to begin with the finished lower receiver. Begin by placing the lower receiver on a vise and installing the magazine catch, followed by the bolt catch, pivot pin, safety selector, and pistol grip. Next comes the trigger assembly, which includes the trigger, hammer, and the trigger guard.
Once that is done, install the buffer tube and take down pins. You can also dent the castle nut of the buffer tube with a punch and hammer for extra caution.
Now, move onto the upper receiver and install the ejection port cover, forward assist, barrel, gas block, and handguard, followed by the bolt assembly.
Once the lower and upper receivers have been completed, install any other accessories like mounts and suppressors. Make sure to lubricate all the parts after each step of the assembly so the rifle functions properly. In case you want a detailed manual of instructions, please refer to the video mentioned below.
Conclusion
When it comes to customizing your AR-15, keep in mind the purpose you will use it for and plan accordingly. You should try to address any comfort or ergonomic issues with the grip, trigger, and handguard by upgrading to the best-fitting accessories you can find. High-quality magazines and sights can also make a big difference in your shooting experience, as you can reload faster and more reliably with good magazines and shoot more accurately with the right scope.
Building an AR-15 from a build kit is a great way to learn more about the workings of your rifle. It also provides a high level of satisfaction through knowing youโve done it yourself!
