How to Make Sure Your Cheap AR-15 Build Kit is Good to Go

Last Updated on April 9, 2024.

The AR-15 is the most popular centerfire rifle in America. Part of the reason is that you can assemble your own from a parts kit with relative ease instead of buying a complete unit.

The ubiquity of AR-15 parts on the market makes it possible to build your own on a limited budget. However, the less you’re prepared, the more likely you’ll run into problems. Find out what you need to make a safe and fully functional budget AR-15 build, allowing you to save significant amounts of money.

Initial Considerations

It is tempting to jump into the world of AR-15 building as soon as you can. However, if you’re looking to save money and keep your overall build costs as low as possible, you first need to establish what you’ll need (and what you already have) to complete a build and how much you’re willing to spend overall.

While it is generally true that what you save in money has to be spent in time building and testing your rifle, it’s easy to underestimate how much you’ll spend on an AR-15.

Many gun enthusiasts have started cheap $500-$600 builds, only to spend over $1,000 by the time the rifle was ready to shoot.

Unfortunately, there is more to the cost of an AR-15 than the parts it comprises. The most significant factor to swelling costs is tools. You will need a set of essential tools to ensure that the assembling process goes smoothly, and if you do not already possess some of them, you will have to factor their cost into your budget.

However, once you have access to these tools, not only will they help you build your AR-15, but they will also help you maintain and upgrade it or even assemble more builds, making them worthwhile long-term investments.

Essential Tools

In a nutshell, you need the following tools to build an AR-15 smoothly:

  • dedicated workbench
  • bench vise
  • Vise blocks for your upper and lower receivers
  • An AR-15 armorer’s wrench
  • Wrench sets: Hex, Allen, star, torque
  • An AR-15 punch set
  • hammer
  • flat-head screwdriver
  • roll pin holder set


Although you can assemble your cheap AR-15 build kit on your kitchen table (and many enthusiasts have), it isn’t the ideal work surface.

Consider investing in a dedicated workbench. Not only will it provide you with a place to install your vise and vise blocks, but you can also store and organize your tools around your workbench.

Your workbench can be made out of anything such as wood or metal, as long as it’s sturdy. You can even build your own if you have the skills to do so.

Bench vise and vise blocks

The most critical tool for building an AR-15 is the old-fashioned engineer’s bench vise. A vise lets you hold your AR in place while working on it and assembling it, freeing both of your hands for installing or removing parts. 

Pair your bench vise with a vise block to hold your lower and upper receivers in place. The top choices for gunsmiths nationwide are the Geissele Reaction rod for the upper receiver and the Magpul BEV for the lower receiver. 


The AR-15 armorer’s wrench and the ½” torque wrench are essential for installing barrels, barrel nuts, castle nuts, and specific muzzle devices.

Other essential wrench sets include Hex wrenchesAllen wrenches, and star wrenches. Consider using a driver set with interchangeable heads, as they are more convenient and take up less space than multiple sets of individual wrenches.

Other tools

A complete punch set for AR-15s should be made of steel and have every size you need to remove and drive in your rifle’s roll pins. To avoid losing them, consider adding roll pin holders to your toolbox.

You can use any generic hammer and any flat-head screwdriver you may already possess. The hammer’s purpose is to be used in conjunction with the punch set, whereas the flat-head screwdriver is for installing your pistol grip.

Essential Parts

When selecting parts for a cheap AR-15 build kit, it is critical to avoid spending money on unnecessary accessories. Although you can always upgrade it later, you must focus on getting a basic, functional rifle first.

Essential upper receiver parts

  • Stripped upper receiver: There are three types of upper receivers sold on the market: barreled uppersstripped uppers, and complete uppers. To save the most money, buy a stripped upper receiver and purchase the other parts separately.
  • Barrel: Use a standard mil-spec barrel. Keep in mind the legal definitions of a pistol and a rifle when choosing your barrel length. If you’re building a rifle, you must buy a barrel at least 16” long. If you’re assembling an AR pistol, you must use a stabilizing arm brace instead of a stock.
  • Muzzle device: The cheapest option is the A2 flash hider.
  • Gas block: On a mil-spec AR-15, the standard A2 front sight also acts as your gas block.
  • Gas tube: The gas tube will also vary based on the type of AR you are assembling. A rifle will have a gas tube length of roughly 15”, while a pistol will only be about 6.75”.
  • Handguard: The handguard is an essential piece because it provides protection and allows for further upgrades. If you plan to upgrade your firearm in the future, it may be important to get a slightly more expensive handguard.
  • Charging handleCharging handles are essentially universal on the AR-15, so be ready to purchase one for your build.
  • Bolt carrier group: The bolt carrier group or (BCG) is responsible for the semi-automatic fire of the rifle. 
  • Dust cover: While not absolutely necessary for the firearm, it keeps the gun clean and helps it last longer.

Essential lower receiver parts

  • Stripped lower receiver: Purchase a stripped lower receiver and the other components separately to save more money.
  • Pistol grip: Pistol grips are a relatively cheap component that can significantly increase the accuracy of the weapon.
  • Buffer parts: Comprises a buffer tube, buffer, and buffer spring.
  • Lower parts kit: Comprises a trigger, hammer, fire selector, bolt release button, and magazine release button.
  • Stock or brace: Install only on a build with a 16” barrel or more to avoid illegally manufacturing an SBR. Otherwise, install a stabilizing brace.

Note that the ATF legally considers the lower receiver to be a firearm, which means it is regulated like one (must possess a serial number, requires a NICS background check to purchase one.)

Other parts

  • At least one magazine. Check your local magazine capacity laws to make sure it’s legal in your area.
  • Sights: If you opted to install a mil-spec A2 front sight, you only need to add a rear sight to aim your rifle correctly. Use any mil-spec compatible rear sight or carry handle. Otherwise, buy a complete sight set (front and rear).

Even When Building An AR-15, Shopping Smart Helps Save Money

When reviewing the list of tools you need to build an AR-15, take a look at what you have in your garage, workshop, tool shed, etc. and check off anything you already possess.

If you paid attention to the list of essential parts, you might have noticed that it doesn’t include popular accessories like muzzle brakes, tactical lights, laser sights, or optics.While useful in the right hands, not only are they expensive, but they are also not required in cheap AR-15 build.

You can also check out:

True Cost of Buying AR-15 Rifle

Beginner's Guide to AR-15 Lower Assembly

Best Affordable AR-15 Build Kit

Best AR-15 Lower Vise Block