How to Choose the Best AR15 Lower Receiver:
There are a wide range of lowers available in today’s marketplace. Design, unique features, coatings, price, and types of material are just some of the options to consider. I’ll share my opinions based on years of research and experience. After reading this article, you’ll hopefully be able to feel comfortable choosing a lower that fits your needs and your budget!
Let’s start with the types of material to consider.
While there are some polymer lowers available, I’d suggest staying away from those and only consider lowers made from aluminum which is a metal. Yes, aluminum is a metal. In fact, it’s the most abundant one found in the earth’s crust. That being said, there are two types of aluminum lowers to consider: 6061 and 7075.
Of these two types, there are three main characteristics to compare:
- Cost: You’re going to pay a premium for 7075 over 6061. Could be as much as $50-$100 more for a lower made from 7075. Even though it’s price per pound isn’t nearly that much more than 6061. Further, 6061 and 7075 are both used for aerospace and automotive components, therefore either is very much up to the task as a firearm.
- Material Strength/hardness: 7075 is quite a bit stronger than 6061, nearly two times. However, 6061 should NOT be considered weak. Both of these alloys are strong, resist pressure, don’t easily deform or crack and are widely used in the aerospace industry.
- Resistance to Corrosion: 6061 is more corrosion-resistant because it has a higher percentage of aluminum in its chemical composition (98% vs 7075 at 90%) and because its other primary alloying components are silicone and magnesium. Whereas 7075’s primary alloying components are copper and zinc. The copper in 7075 reacts with the environment and causes corrosion.
Read here for further info: 6061 vs 7075: Which is the Champion Alloy link text
4. Coating: The most common types of coating for lowers are anodize and Cerakote. There are some pro and cons for both types and each can slightly effect surface hardness and corrosion resistance. I prefer the more even and wider range of colors available through Cerakote finishes but you’ll pay a premium of $35-$50 for a receiver with this option.
Read here for further info:
Which coating is better? – Cerakote vs. Anodizing | Cerakote Vs.
5. Manufacturing (how is your lower made?) Cast Lower– Produce a lower by pouring molten aluminum into a sand mold. This is the cheapest way to make a lower and produces the poorest quality. Even though, the lower is still high enough quality to be used for your build. This should be the last option to consider. Forged Lower– Heated aluminum is compressed between two steel dies into a basic shape but then must go to a CNC mill to be machined to final specs. Some features remain forge, therefore some tolerances can vary for these features. Further, because the forging dies are very expensive to alter, changes in design and customization are not really and option. Forging does however create a strong end-product. Additionally, your lower will most likely be a two-piece design because trigger guards are generally too thin to be included in the forging process, so you’ll need to buy a separate trigger guard. Billet Lower– machined from solid billet aluminum offer the best options for: customization, nicely machined detailed features, and very close tolerances for all features because it is 100% CNC machined. Also, it will be a one-piece design, so no extra parts needed to make it complete. This is the best preferred type of lower to consider.
