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80% Arms sells AR-15 and .308 80% Lower Receivers, 80% Lower Jigs and other accessories which allow you to legally build a firearm at home in most states.
We utilize state of the art 5-axis CNC machines to mill all our .308 and AR-15 80 percent lower receivers to incredibly precise tolerances using premium billet aluminum.
We also offer our patented AR-15 and .308 Easy Jigs which is the first 80% lower jig that makes it ridiculously easy for a non-machinist to finish their 80% lower in under 1 hour with no drill press required.
Products manufactured by 80% Arms carry a lifetime warranty against manufacturing defects. We will promptly replace or repair any product that we determine to be defective.
AR-15 Buyers Guide - 80 Percent Arms thumbnail image

AR-15 Buyers Guide - 80 Percent Arms

80 Percent Arms   |   Oct 1st 2018

AR-15 Growing Popularity

The explosion of popularity surrounding the AR-15 is an amalgamation of a few key factors like political climate, pop culture and significant product developments. At the core of many people, reverse psychology can affect many people even at the subconscious level. So if the politicians are screaming at the top of their lungs, “Less! Not more, less!” (In reference to gun ownership) then a person with critical thinking skills might be curious as to what all the fuss is about.

Another way of explaining this is when you tell me I can’t have something, the child in me simply makes me want it more.

With the way our value systems work and our tradition of rights guaranteed to us via the Constitution, it’s also easy to be frustrated in the constant struggle to maintain and, in many instances, reclaim the 2nd Amendment for the average American. So whenever an emboldened administration publicly announces their desire to reduce gun sales, ownership and increase gun control it inevitably makes demand for guns skyrocket as people fear they may one day not be able to have access to those products anymore.

Pop culture is also a significant factor as well. All the kids that grew up playing first person shooter video games are now of legal age, well into adulthood and will perhaps be interested in trying the real thing out now. Hollywood movies and TV shows have always been a huge driving force as well in American consumerism, which has created hype and popularity around brands, products and lifestyles. While it’s easy to romanticize how fun or cool the newest guns and gear may be, more importantly, this is the American way of life — whether you buy a factory built gun or make one yourself the right of the people to keep and bear arms, shall not be infringed.

Fundamentals of Buying First AR-15

Speaking of making your own guns, if you’re looking to get your first AR-15 and you’re considering building it from the ground up you are way ahead of the curve. Most first time buyers will opt for a store bought gun for lack of understanding how all the individual components come together to make a fully functioning firearm. While there is a lot of information and factors to consider we hope to break the fundamental information down so it makes it easier for you to jump right in and figure out what this is all about.

Obviously, we love building our own guns. But because we are intentional with the use of our AR-15’s, that informs us on what parts to best use when purchasing parts to put it together. Think of this like modifying your car. Some light research will tell you what parts your car likes or what parts will dramatically increase its comfort or performance. It depends on what you’re going for right? It’s the same concept with an AR15. Familiarize yourself with these key components so you’ll understand how some AR15 parts modification will help specialize it for one use, but potentially limit it in other uses as well.

AR-15 Configurationsar15 with pelican case

What do we mean by AR15 configurations? Have you noticed that some AR15 rifles are longer than others and that they might have different attachments on them? Well based on the barrel length of an AR-15 that is very telling of what a specific rifle is capable of excelling at and what it’s shortcomings will be function wise. On top of AR15 configurations you’ll also have to factor what kind of ammunition you are using to have the full understanding of your rifle’s ballistic capabilities.

Rifle Length

Any AR15 rifle that has an 18” barrel or longer is considered to be ‘rifle length.’ Typically, AR15 rifle length barrels will be 18”, 20” and 24” long. Having this long of a barrel really lets you maximize your caliber’s velocity which is great for terminal ballistics but also for better stabilizing the bullet on its flight towards the target. With a long barrel, the recoil is very soft and comfortable to shoot which is why many precision shooters will use a rifle length setup for competitions. However, don’t expect to be clearing any rooms with an AR-15 this long or to defend your home with it unless you live on a massive property. You can expect rifle length builds to be heavy and not as easy to maneuver with.H3: Carbine Length

Technically, any AR15 with a barrel shorter than 18” is considered a ‘carbine.’ However, the carbine length category can be broken down to even more specific sets of AR15’s built with a variety of shorter barrel and gas tubes.

Mid Length

Mid length AR15’s will have 14.5” or 16” barrels. The reason for this is because for civilians to own AR15’s that aren’t regulated under NFA, they must have a barrel length of 16” at the minimum. What some gun owners will do is utilize a 14.5” barrel and pin or weld their muzzle device to the barrel so that it counts towards the barrel’s total overall length. Mid length and rifle length AR15’s are known for how comfortable they can be to shoot because the longer the system, the less perceived recoil there is along with a smoother cycling action of the bolt carrier group. A couple companies do make shorter mid length barrel setups that are 12.5” but those are outliers and do not represent the majority of the market.

Pistol Length

Pistol length AR15 barrels will be 10.5” and includes anything shorter than that. Shorter barrel and gas systems in AR15’s operate faster because there’s a high volume of gas sent back towards the shooter which can make the cyclical action of the BCG very violent and difficult to manage if not paired with a good muzzle device and heavier buffer weight system.

Barrel Types

One of the biggest factors in determining whether a build is budget vs. high end AR15 is the barrel! While deciding your barrel length is important, a lot of people will neglect to do the research of barrel types. The barrel you choose will have a direct affect on your accuracy and its lifespan so choose wisely and do your homework!


Do you want a barrel with cut rifling, button rifling or made by being cold hammer forged? These are the three major types of rifling and each has their own pros and cons. Learn more about them in our previous blog where we dive into rifling.

Chrome Lined

Most AR15 barrels will have either chrome lined barrels or stainless steel barrels. Typically, you’ll find chrome molly steel barrels that are lined with chrome within the bore. If you live in a state that is very humid during the non-winter months or expect to use your AR15 in wet, saltwater environments then definitely opt for a chrome-lined barrel. The chrome lining offers superior corrosion resistance, extended barrel life and makes them easy to clean. One downside to chrome lined barrels is that they are not completely reliable in medium to long range distance shots (i.e. 300 yards). However, most shooters will find that this shortcoming is negligible as it’s difficult for most shooters to become so proficient and shoot often enough to be able to notice this flaw. Most barrels will last around 10,000 rounds which is why most shooters will never outshoot their barrels in the first place.

Stainless Steel

Stainless steel barrels are also known as match grade barrels. Under 300 yards, they don’t offer any benefits or advantages over other barrels. But once you start shooting at targets past 300 yards that’s really where stainless steel barrels really start to shine. However, the trade off is that these barrels are not chrome lined. That means that these barrels wear out faster, are harder to clean and are not very durable against corrosion. If you do shoot in competitions you should know that the barrel will start to degrade and lose its edge anywhere between 3 to 5000 rounds. For a while, stainless steel barrels were very popular just for how they looked; shiny.


Nitrided barrels are all the rage these days. In fact, they are more commonly known as the standard for any AR15 barrel. Corrosion resistance with barrels that have gone under the salt bath nitriding process are actually four times more resistance than chrome lined barrels. While chrome lined barrels protect the bore of the barrel, it doesn’t protect the outside of it. Nitrided barrels are protected all around, inside the bore and out.

Nitriding is also more inexpensive than the chrome lining process so those savings in production cost are also passed on to the consumer in the form of affordable barrels. Accuracy is also very good with nitrided barrels because the nitriding process does not affect the barrel’s polish which gives it a very consistent finish. Consistency can be seen as the same as accuracy. There’s really only one downside to nitrided barrels compared to chrome barrels and that’s heat resistance, or lack thereof — which is why I almost always wear a glove on my support hand. The handguard can get hot!

Caliber Flexibility

AR-15s are great and known for their extreme modularity, which of course we are all about. You not only can build an AR15 rifle in several configurations, you can also use several different calibers for different purposes. If you don’t count all the Wildcat and experimental cartridges out there; commercially, there should be anywhere between 8 to 20 widely available calibers that the AR-15 platform can support including .223 Wylde, .223 Remington, 5.56 NATO, .300 BLK, .22 LR, .458 SOCOM, 6.8 SPC, 7.62x39mm or even 9mm Luger.

Our Recommendation: Build Your AR-15

If you've landed here, I'm willing to bet you've already made the decision to build your own AR15 rifle or Glock® style pistol, you're just looking for help on the “how.” And you aren't alone. If you're new to firearms, the prospect of building your own seems like an incredible challenge. Even if you're just new to these platforms specifically, it seems like a lot of information, different tools and a lot of places to screw up. Thankfully, it really is easier than it looks and we're here to walk you through the entire process.

Building with Quality Parts

There are several manufacturers that make 80% products like lower receivers and polymer pistol frames. It’s important to buy quality parts so that you don’t run into parts compatibility issues or poor tolerances. 80% Arms only sells products that have been test fitted so that when you buy from us you can be sure that you’re going to have great fitment and the best tolerances whether you’re buying lower receivers from us or milling other companies’ lowers (mil-spec) with the Easy Jig® Gen 3. If you do run into any problems be sure to let our customer service team know so that we can help you troubleshoot and diagnose the source of your issue and potential solutions.


While we offer a few different models, for the purpose of this walkthrough, we're going to stick to the latest, greatest, and easiest jig on the market, the Easy Jig® Gen 3. If you're looking for the easiest jig on the market, that's the one to get. You don't need any specialized tools, just a handheld router and a drill. Things you either likely have at home already, or if not, you can easily pick up at any hardware store.


Of course, any special tool needs special tooling, so you're going to want to pick up an Easy Jig® Gen 3 Tool Kit also. All you need to do is check which size your router is compatible with. Don't see your size? Measure the thread and pitch of the spindle to figure out which size you need. Don't have a router? Buy the DeWalt DWP611, and get a Size C/3 toolkit. Easy.


If you've got the jig, the bulk of your shopping is over. What you need now is an 80 lower, and there's plenty of options to choose from. You're basic decision is going to be choosing between an AR15, and AR9, or an AR10/308. Let's take a look at your options.

AR15 80% LOWER

By FAR the most popular, this is what most people build. Dubbed "America's Rifle", the venerable AR15 has become a staple in most gun-owning households. Not just the ideal defense weapon, it is also great for hunting, precision shooting, 3-Gun competitions, you name it. Our most popular lower is the Black Anodized AR-15 80% Lower. Common calibers include .223/5.56mm, .300 Blackout, 7.62x39mm, and 5.45x39mm. More exotic calibers are the .458 SOCOM, and the .50 Beowulf. We also have other color AR15 80 lowers available.


The AR9 has been gaining in popularity the past few years, from a competition gun for Pistol Caliber Carbine (PCC) class shooters, to people who just like to plink and shoot for cheap. 9mm ammunition typically runs about half the cost of 5.56mm rifle ammunition, so you can shoot more, for less. We have several AR9 80% Lowers to choose from. You can even mill these on the same setting as the AR15 on your Jig, to make it as simple as possible.

AR10 80% LOWER

Looking for something with a bit more knockdown power? The AR10 is capable of handling .308/7.62x51mm, 6.5 Creedmoor, and other full-power rifle rounds. We offer a selection of AR10 80% Lowers.


Now that you have everything you need to take an 80% lower into a 100% lower (and a legal firearm), we're going to need some additional parts to make that firearm functional as well! Luckily for you, most of our components come pre-assembled, and the AR-15 is jokingly referred to as a"lego set for adults" for a reason. The parts are all very easily interchanged, and the possibilities are endless.


First, you'll need an upper receiver. This is the other half of the AR platform, and you don't have to do any work here. We offer pre-built configurations that drop in with two quick push-pins, making it simple to choose what you want, and start shooting. View our Complete Upper Receivers.


This is a no-brainer. Get the CMMG lower parts kit. It’s as stock as they come but it’ll get your AR-15 setup faster and get you shooting even sooner. If you want to upgrade the pistol grip or the trigger you can easily do so later on with something from Magpul and a drop-in trigger of your choosing.


At the minimum, you can start out with a standard stock and buffer tube assembly. Then, you can upgrade later on to change out your stock to something else like one of Magpul’s or any of the hundreds of stocks being sold on the market. The new stock will just slide right on.

Final Thoughts

So as you are thinking about buying individual AR15 parts or a store bought gun that’s pre--built. Keep these major components in mind so you have an idea of what you’re getting yourself into. Being familiar with all the main parts of an AR15 also helps you find the best prices rather than just paying the first asking price you see whether that’s online or at a brick and mortar store.