The AR15 Upper Receiver: A Comprehensive Guide

When creating an AR, an 80 percent lower is a good place to start. It is for this reason that you will attach a variety of components, including an upper receiver. However, how would you choose an option fit for your AR?

To begin, you should be aware that today’s upper receivers come in a variety of styles. For your rifle, you have the A1, A2/A3, A4/M4, and LR-308 – a few high-quality full receivers to choose from.


AR is a multifunctional platform with a wide range of customisation options to better suit your everyday needs. With this in mind, the upper receiver you select should be compatible with your shooting technique, firing method, and ideal style.

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You do, however, have options.

Eugene Stoner’s ArmaLite AR-10, coupled with one of the earliest M16A1-style upper receivers, was initially shown a long time ago. With a quick sight aperture, a coordinated back sight gap, and the characteristic carry handle, the A1 upper receiver is still exceptional today.

A2/A3 Upper Receiver — The US Military soon realised that Stoner’s distinctive A1 upper receiver needed to be improved, therefore the A2/A3 upper receiver was developed and deployed in conflict zones across the world. The prominent carry handle is still present, albeit slightly larger, and significantly improves the overall group and rear sight gap.

Upper Receiver A4/M4 — A cutting-edge firearm aficionado necessitates an advanced upper receiver, but one that is built on the tried-and-true upper receivers of the past. The A4/M4 upper receiver was designed with the AR-15 in mind, and it included a stripper receiver that allowed you to use any iron sight, optic, or long-range scope you wanted. Furthermore, the A4/M4 system ensures greater reliability with widely available ammunition, such as 5.56 NATO.

The AR.308 upper receiver, which is available for AR-10 and SR-25 rifles, is a popular choice among AR builders if you prefer a heavy-hitting ammunition. When it came to optics of any kind, both models had a naked upper.


However, if you’re building an upper receiver without any prior preparation to go with your 80 percent lower build, you’re not sure what equipment and materials are necessary. You’ve come to the right place.

The following are the tools you’ll need to finish your project:

A metal punch set will avoid scrapes or damage to the receiver while allowing you to insert pins quickly.

Hammer – A metal mallet, or one with an elastic end, will protect your receiver from serious damage.

12-inch Torque Wrench – When installing barrel nuts, you’ll need the right torque. Individuals, don’t forget to use a torque wrench!

Wheeler Torque Wrench – When installing a gas block, a Wheeler Torque Wrench is the tool of choice, but it also works for particular scopes.

AR-15 Combo Tool — A combination tool with components for the barrel nut, stock, castle nut, buttstock tube, and compensator, as well as a force/torque wrench, custom-fitted for the ar 15 parts kit.

Feeler Gauge – As previously stated, you must adjust your gas block to the proper gas setting. With a feeler gauge, you can make sure yours is set to 0.025 inches from the barrel shoulder.