Guide on the AR-15

We’ve talked about numerous things in our education center including things to take to the range, making a lightweight AR, gas systems, barrel lengths, and cleaning and maintenance. Now it’s time for a general guide for the AR-15. Whether you’re new to the AR world or you know your way around a rifle, hopefully you’ll learn at least one new thing in this post. The AR-15 is a very versatile, reliable, and military-inspired civilian firearm. Everything has a story, so before we get into the nit and grit, let’s talk about the history of the AR-15.

AR-15 History

“AR” has been used as an umbrella term throughout the last 60-70 years because there have been many variations of semi-automatic rifles made by various gun manufacturers. Throughout the 1950s, Eugene Stoner developed the 5.56x46mm AR-15 as a lightweight version of the 7.62x51mm AR-10. Stoner was working at ArmaLite, Inc at the time which is where AR coins from. “AR” is short for “ArmaLite Rifle,” not the commonly misconceived “Assault Rifle.”

Armalite originally made the AR-15 as a military rifle but had a hard time selling it. In 1959, ArmaLite sold the AR-15 to Colt. Two years before the Vietnam War started in 1963, the U.S. Military assigned Colt to produce the standard-issue automatic rifle. This rifle was used in the Vietnam War and was called the M-16.

The M-16 was a huge success and Colt started to manufacture a semi-automatic version that they could sell to law enforcement and civilians. They marketed it as the AR-15 until their patents expired in the 70s. After that, other gun manufacturers began making extremely similar models and the AR-15 turned into a general term for all types of AR inspired rifles.

Buy a Complete or Customize?

If you are new to the AR-15 world and are looking to own your first AR-15, we suggest buying a complete set from a trusted manufacturer like our sister company Primary Weapons Systems. Buying a complete rifle also saves you from potential hassle and worry of finding a solid warranty and all those other business aspects you have to worry about. Also, if you’re just starting off, it’s going to take some shots to really figure out what you like and if you want to invest more time and money in your AR-15.

Although, for those who are more experienced and know what you want, there is something extremely satisfying about putting together your very own, unique, customized AR-15 or “Franken-gun.” All those custom AR parts are personalized by you. That’s special. As mentioned in our last blog, assembling and disassembling your AR-15 is a relatively simple process. With this, you get to pick and choose what goes on your weapon. Look at our available inventory to start, continue, and/or end your custom AR part journey.

Now let’s take a deeper dive into the AR-15 anatomy.

Bolt Carrier Group

We’re going to start with the bolt carrier group because it is the engine that drives the weapon. The bolt of the gun is housed within the bolt carrier making the bolt carrier group. The bolt carrier group is moved back when you pull back the charging handle. When you let go of the charging handle, the bolt carrier group moves forward with a round from the loaded magazine and puts a round in the chamber. When pulling the trigger, the hammer hits the back of the firing pin which is located within the bolt carrier group. The firing pin then strikes the cartridge’s primer which sparks the gunpowder, causing an explosion that propels the bullet outward. This whole process happens in the blink of an eye.

If you’re new to ARs then it is important to note that your AR can only fire semi-automatically, which means you pull the trigger and one bullet fires. This is the main difference between military rifles and civilian rifles. Military rifles have the ability to fire 3-round burst or fully-automatic as well as semi-automatic.


We talked about barrels in our previous blog, “The Perfect Barrel Length for Your AR-15” but we are going to go into a lot more detail here. Although, we aren’t going to go into too much detail with length because that post covers that area. So, let’s start with barrel chambering. The chamber is the part of the barrel where the round sits before firing. There are a plethora of chamberings from the most common 5.56x45mm NATO, to the bigger 7.62x51mm, to the tiny .22LR, and even the monstrous .50 Beowulf. The 5.56 barrel and the .223 barrel are the most common but there are a couple of details you should know.

  • A 5.56 barrel can shoot both 5.56 and .223 calibers
  • A 2.23 barrel cannot shoot a 5.56 round. Only the 2.23 round

Barrel Length

For barrel length, we are keeping it short and sweet because like mentioned previously, we have a blog that covers barrel length. But, a few takeaways are that the longer the barrel, the more velocity you have. A longer barrel does not necessarily mean more accurate. But it does mean that the elements won’t have as much of an impact because there’s less time to affect the movement of the bullet.

This law differs from state-to-state, but federally, you cannot have a barrel that is under 16”. The 16” barrel is good for up to 400 yards, but after that, you’re going to want a barrel that is longer or a bullet that is heavier.

Barrel Twist Rate

This is for the ideal bullet weight and length. The longer and heavier the projectile, the faster the twist rate. This is determined with (1 x inches). For example, the most common twist rate is 1:9 or one twist per 9 inches and that is for a 55-grain bullet.

Barrel Material

Moving on with barrel material, there are several materials your barrel can be made out of:

  • 4150: Steel barrel
  • 4140: Steel barrel with 10% less carbon than 4150
  • Chrome Moly, CMV or Chrome Molybdenum Vanadium: different materials but the same as the 4140
  • Stainless Steel: A little more accurate but has a shorter lifespan

We would recommend 4140 because that is all that is necessary.

Gas Systems

We’ve talked about gas systems and gas blocks in our previous post, The Advantages of Adjustable Gas Blocks, but again, we will go further in-depth here.

The purpose of gas systems is that it captures the gas from the previously fired bullet and the gas tube sends it back to the chamber, pushing out the old cartridge and loading a new one. There are two major types of gas systems and those include direct impingement and piston.

Direct impingement forces hot gas and carbon into the receiver and chamber. That’s as detailed as direct impingement gets. It is very commonly used and it is cheaper and more accurate than the piston. Pistons are used mainly if you’re pulling your weapon from out of the water or in an extremely dusty environment.

For beginners, we recommend gas blocks that are already attached to the front sight because it is convenient, robust, and is cost-efficient.

But, if you’re looking to upgrade your AR-15, you can grind down your front sight base and have a free-floating barrel. Although, there are some gas barrels that are adjustable so you can choose the perfect amount of gas for any unnecessary recoil when firing your weapon. Check out our gas blocks and tubes here. If you know you want to add attachments to your AR, then just start with a free-float handguard.


Handguards are crucial because they keep you from burning your hand on the barrel. They are also important if you’re looking to upgrade your AR-15. They allow you to put multiple attachments like scopes, flashlights, grips, etc. There are some handguards that come with a “quad-rail” which allows you to put an attachment on all four sides of the handguard. Free-floating handguards are greatly beneficial because they are a lot lighter than standard-issue and they also allow for more consistent shots because there’s nothing touching the barrel along the handguard. Check out our selection of handguards here and finish your complete upper assembly!


We recommend sticking with the standard-issue Mil-Spec trigger if you’re beginning. It will feel gritty at first but that will eventually wear off. If you are looking to upgrade your AR, we have heard a lot of people make their trigger the first upgrade they ever do. This is because this is one of the best ways to improve your accuracy.

Wrap Up

There are a lot of aspects when talking about the AR-15. It is extremely versatile and you can make your own customized AR. There is a lot more to talk about, but this general guide will hopefully lead you to the right AR-15 or the right AR accessory. Make sure you check out our AR accessories and get your own custom AR parts!

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