What are the four types of lower receivers?

Lower receivers are the foundational component from which firearm enthusiasts embark on a new build. They’re inexpensive, offer unparalleled flexibility, and are favored by many for their innovative designs. Personalization options are also available, and with an 80% lower receiver, you’ll often avoid much of the hassle and paperwork associated with buying a fully built gun. In some cases, you’ll even be able to escape state fees. 

80% lower receivers are more varied than many imagine, though, and there are four distinct types to choose from.

1. Billet

Billet might be considered the highest-end receiver, and with good reason. The production processes associated with these components make them the strongest around. Billets are cut from a solid block of steel using a CNC machine. That alone is enough to make them incredibly durable, but the receivers then undergo an in-depth crafting process. Rather than just tough, these receivers come with a professional finish. They’re often customized and are exceptionally lightweight. However, with such quality comes a higher price tag, so billets might not be the best choice for an entry-level build.

2. Forged

If you’re looking for a no-frills, cheaper receiver that’s still exceptionally durable and up to the rigors of continued use, then forged is the way to go. These are the most popular type of receivers and are (usually) the first ones that newcomers will come across. They leave a lot to be desired in the aesthetics department (they aren’t nearly as stylish as billets), but they’re tough and functional. They’re cut from aluminum and then bashed into the desired shape by hydraulic hammers, so the process is quick and cost-effective. You’ll find these receivers widely available from suppliers like https://www.80percentarms.com/80-lowers/ since they’re favored for their all-round credentials. 

3. Polymer

A controversial choice, polymer receivers are nonetheless growing in popularity. They’re substantially cheaper than the other types on the list but generally considered to be lower quality. This raises some questions over safety, and some gun enthusiasts will outright shun polymer receivers. Polymer isn’t as tough as aluminum, which accounts for the lower price tag and (supposedly) decreased lifespan. It’s a matter of much debate, but one thing’s for certain: polymer receivers are getting more popular. They don’t need to be coated in the same way that aluminum versions do, so they retain their natural color for longer without fading.

4. Casted

Another type that’s frowned upon in gun enthusiast circles, casting, doesn’t provide the same strength as an aluminum receiver. These are made by pouring molten metal into a cast. When the metal has solidified, it’s ready to use, with minimal additional manufacturing processes required. Casting is certainly quick, it’s definitely cheap, but it lacks both the finesse and the durability of the other processes listed. As a result, some stores don’t offer cast receivers at all, and many firearm builders will tell you to avoid this production method. Safety can be an issue and, even though the receivers are finished in a CNC machine, they aren’t really up to the standard of an aluminum or even polymer alternative.