DIY: How to Build a Rifle

Last Updated on June 8, 2024.
DIY How to Build a Rifle

If you’re interested in knowing all the ins and outs of your weapon as well as saving yourself money, you should consider building a DIY rifle. Once you have located the lower receiver, you can pick out each part to your exact specifications and at your leisure.

Why You Should Build a Rifle

If you would like to spread out the cost of building a rifle, collect the parts slowly, and have some technical skill and a place to work, you are capable of making your own AR-style modern sporting rifle or MSR.

For many, a gun hobby is an expensive habit. But building your rifle is a great way to save on parts and labor as well as spreading out the cost over many months. Creating your custom AR MSR can take however long you want, and you can either buy a piece at a time or buy a kit to get it done. 

A custom-built rifle will fit your expectations and needs much more closely than an MSR you pick up at the store. You will also gain a good deal of satisfaction from the process and know your rifle like the back of your hand when you’re done. 

If you feel trepidation about starting, take the advice of a gun expert who has the experience of building many rifles under their belt and just start building. Additionally, with the number of how-to videos available on the Internet, you will find many excellent instructional resources.

Plan Out Your Rifle’s Design

If you’ve been wondering how to build a rifle, you first need to be introspective. What kind of rifle do you need? How much are you willing to spend? What is your skill level comparative to your expectations? Once you have figured out the answer to these questions, you can design a custom-built AR MSR to fit your needs perfectly

Three limiting considerations are the cost of the parts, the cost of the tools (and whether you have access to them), and the time it takes to build the weapon. Before you embark on this ultimately satisfying endeavor, make sure you have the time, money, and skills to get the job done.

​Parts You Will Need

The six central components of a rifle are the lower receiver, the upper receiver, a gas system length, the handguards, the barrel, and the bolt carrier group or BCG. 

Out of all the components, the one considered lethal by the law is the lower receiver, which you have to buy from a licensed federal firearms dealer and sometimes undergo a ​background check.  

Lower Receiver 

There are four types of a lower receiver – cast aluminum, billet lower, forged aluminum, and a polymer lower receiver. The polymer lower is one of the more modern renditions, and some shooters are skeptical that this lightweight material might break at the front hinge pin. This rarely happens. 

An aluminum cast lower is the cheapest, as molten aluminum is poured into a mold and hardens. You can buy one premade for a convenient price point.

Upper Receiver

AR MRS has two systems for upper receivers – a piston system and a direct impingement system. 

  • Gas piston system – In this type of upper receiver, a piston is secured to your lower built throughout circulation. Although cooler after many rounds, there is more recoil with a piston system, so your accuracy may suffer
  • Direct impingement system – This type of upper receiver is more popular and precise than a piston receiver. Gas from combustion is used to eject the spent casing and chamber a new shot. 

Many AR owners (and builders) like the lightweight direct impingement system for its focused precision and low cost. On the other hand, some prefer the piston system because it’s more adaptable to different calibers and shoots cleaner and cooler than the alternative. 

Gas System Length

Choosing the right gas system is crucial as it will determine how usable and reliable your DIY weapon is. With too little length, your bullet won’t leave the muzzle when the suitable amount of gas has been transferred. 

In other words, if the gas length system is too short, the rifle won’t work.

If the gas system length is too long, your bolt will have too much gas, which will result in leakage. This leakage can easily and irreparably damage your rifle’s entire inner workings. 


Many upper receivers come with handguards, but if yours doesn’t, then you need to buy some quality ones. There are cheap ones on the market but look for rail guards as they are more compatible with other accessories


When picking a barrel, you should look for one between 10.5” and 16”. These are standard barrel lengths that many manufacturers produce. These barrel lengths also operate most reliably with semi-automatic gas systems.

Also, anything more than 16” will cause lots of backpressure if you combine it with a silencer. This might be a deal-breaker for lots of big game hunters as they won’t be able to take a shot without giving away their position. 

Additionally, consider whether you want a chrome-lined or a stainless steel barrel. Chrome has better longevity. But stainless steel offers more consistent accuracy.

Along with barrel length, think about how thick you want your barrel to be–lightweight contour, standard M4 barrel, or heavy-duty barrel.

Bolt Carrier Group

You do not want to skimp on this crucial component of your DIY rifle. No matter what kind of BCG you use, make sure to stake the gas keys with fasteners that are grade 8 to prevent the hex bolts from shaking loose.

​Skills and Tools

You will need to have a minimal amount of technical skill and tools when preparing for how to build a rifle. An essential tool is a heavy vise bolted to a sturdy work table. 

You will also want a pad to put over the jaws of the vise or padded jaws so that your work won’t scratch your parts. The other integral tool is various pin punches. With different punches at the ready, you can save yourself a lot of headache in the process.

Finally, you’ll need a hammer with brass on one side and plastic on the other.

Wrapping Up

Once you have gathered the right parts and tools, set them all out on an uncluttered workspace in the order of assembly and get to work. The assembly process should take anywhere from two to four hours.

When you’re done, you will have your very own, customized AR MSR to take out on your next adventure.

If you're looking for more great selection on rifles, we recommend you checking out these awesome AR-10 rifles on our recent article.

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