If you’re building your own AR-15 rifle, one of the most important decisions you’ll have to make is which lower parts kit to choose. A lower parts kit (LPK) contains all the necessary components needed to complete the lower receiver of the rifle, so it’s important to get the right one. In this comprehensive guide, we’ll provide you with all the information you need to make an informed decision when selecting the perfect lower parts kit for your needs.

The Three Types of Lowers

When it comes to choosing the perfect lower parts kit, it’s important to first understand the different types of lowers that are available. Generally, there are three types of lowers: billet, forged, and polymer.

Billet lowers are machined from a single block of aluminum, making them extremely durable and strong. They’re also customizable and can come in a variety of colors and designs. If you’re looking for a high-quality and unique lower, billet is the way to go.

Forged lowers, on the other hand, are made by pressing and shaping a block of aluminum under intense pressure. This makes them strong and durable as well, but they don’t offer the same level of customization as billet lowers. However, they’re a great option if you’re looking for a reliable and cost-effective lower.

Lastly, polymer lowers are made from a high-grade polymer material, which makes them lightweight and affordable. They’re not as strong as billet or forged lowers, but they’re a great option if you’re on a tight budget or looking for a lightweight option.

No matter which type of lower you choose, it’s important to purchase from a reputable dealer like 80-lower.com to ensure quality and compatibility with your chosen parts kit.


Compatibility is a crucial factor to consider when choosing the perfect lower parts kit for your build. Not all lower parts kits are created equal, and not all are compatible with every lower receiver on the market. The first step is to determine the type of lower you have – AR-15, AR-9, or LR-308.

Once you know your lower type, you can narrow down your search to kits that are specifically designed to work with your lower receiver. It’s important to note that some lower receivers may require proprietary parts, so it’s always a good idea to consult with the manufacturer or do some research beforehand.

Another thing to keep in mind is the brand of your lower receiver. Some lower parts kits may be compatible with multiple brands, while others may only work with specific brands. For example, 80-lower.com offers lower parts kits that are compatible with multiple brands, including their own brand of lower receivers.

It’s also worth mentioning that some lower parts kits may not include all of the necessary components for a complete build. In these cases, you may need to purchase additional parts separately or opt for a more comprehensive kit.