What Are The Different AR-15 Upper Types?

AR enthusiasts know that when it comes to modularity, few can compare it to the AR-15. But did you know there are different types of AR-15 upper receivers? Ranging from A1 to A4, in this article, we discuss each type of upper receiver, focusing on features and who they are suited for most.

We also discuss some important compatibility factors, such as whether all barrel types match with upper receivers and how handguard length affects upper receiver selection. In the end, you’ll be able to make an informed decision on what type of AR-15 upper receiver to get based on your unique use case.

4 Types Of AR-15 Upper Receivers

Below is a list of the 4 types of AR-15 upper receivers.

1. A1 Upper Receiver
2. A2 Upper Receiver
3. A3 Upper Receiver
4. A4 Upper Receiver

1. A1 Upper Receiver

The earliest version of the upper receiver, the A1 was designed to be simple, lightweight, and effective. It is characterized by its fixed carry handle and rear sight.

2. A2 Upper Receiver

The A2 features a removable carry handle and rear sight, which is also adjustable for both windage and elevation. It also features a thicker barrel profile.

3. A3 Upper Receiver

The A3 is a more modular type of complete upper compared to the A2. It does not have a built-in rear sight. Instead, it has a Picatinny rail, allowing for the attachment of various optics and accessories.

4. A4 Upper Receiver

The A4 is my favorite type of upper receiver. It is similar to the A3, but it is a flat-top upper receiver and is fully modular, including features like a free-floating handguard. Ultimately, your use case and personal preference determine which type of upper receiver to get, but if you want to go full modular, the A4 is the receiver for you.

Which Type Of AR-15 Upper Receiver Should You Choose?

If you want to go for a retro-style build, the A1 offers that classic look. However, if you want a more durable and versatile build than the A1, the A2 can offer that and still appeal to those who enjoy the classical design elements of the A1.

The A3 upper receiver is best for those who want a balance between traditional and modern features. Finally, if you want to go for the fully customizable experience, including options for barrel length, rifle or carbine length gas system, forward assist, and optics, then the A4 is the best upper receiver for you.

What Is The Best Upper Receiver?

The best AR-15 upper receiver is subjective to your specific needs. However, if you want practicality and versatility, the A4 should be your number one choice. If you simply want to connect with the past and are a historical firearm enthusiast, opt for A1.

The A2 and A3 are intermediates between the two extremes – the former still prioritizes that historical look but pays more attention to durability, and the latter prioritizes modularity but still doesn’t go full modular. Shooters should also take the time to learn to build AR-15 upper receivers as well.

Do All Barrel Types Match All Upper Receivers?

In general, both upper and lower receivers are designed to be compatible with most individual parts. However, if you buy a stripped upper receiver and want to add a quality AR-15 barrel or simply upgrade your barrel, it might be a good choice to ensure the barrel matches the upper receiver.

For instance, a barrel designed for a flat-top A4 might not be compatible with an A1 upper receiver group. Also, pay attention to the handguard length, as this will influence your performance with the new barrel.

Does Handguard Length Affect Upper Receiver Selection?

I tend to say yes. Some AR-15 upper receivers just work better with longer AR-15 handguards, especially those designed for a free-floating barrel system.

Also, make sure the handguard blends well with the rest of the AR-15. You don’t want a bulky handguard attached to a sleek lower receiver and upper receiver combo – it just looks unnatural.

Do Complete Upper Receivers Include Bolt Carrier Groups?

The best complete AR-15 upper receivers include an AR-15 bolt carrier group. However, always read the product description before purchasing a complete upper receiver.

If a bolt carrier group is not included and you want to buy it separately, ensure that it is compatible with the ejection port and the rest of the gas system, regardless of whether it’s a mid-length gas system or a rifle-length gas system. You should also be aware of the caliber of your AR-15 before making any mods to your BCG.

Frequently Asked Questions

The Bottom Line

Understanding the different types of AR-15 upper receivers helps you make an informed decision tailored to your shooting needs. Each type of upper receiver offers different features and benefits, so choose the one that best suits your shooting style and desired look. Remember to pay attention to compatibility with barrel types and handguard lengths. Happy shooting!