Lifetime Warranty Lifetime Warranty Made in the USA Made in the USA FREE Shipping on $250+ Free Shipping on all orders $250+!
AR-15LowerReceivers.com – 80% Lowers, 80% Lower Jigs & AR-15 Parts

80 Lower Receiver Buyer’s Guide [2019]

80 Lower Receiver Buyer’s Guide [2019]

Picking the right tools and parts for completing your AR-15 build can seem overwhelming. There are loads of specifications to consider, especially when picking out your receivers. We’re going to make it easy with our 80 Lower Receiver Buyer’s Guide: First, we’ll list all the available types of 80% lowers you can pick from (billet, forged, polymer, or cast). Then, we’ll break down everything you need to know about each one, including the pros and cons:

  • Material
  • Caliber
  • Finish
  • Cost (with jig included)
  • Additional tools required

By the end of this guide, you’ll know everything there is to know about the 80 lower, and which one is best for your AR build. Let’s begin!

80 Lower Receiver Types, Calibers & Finishes

An 80 percent lower can be made from four different materials: Billet aluminum, forged aluminum, polymer, and cast aluminum. Let’s break down each one first.

Billet (6061 T6 aluminum)

Billet 80 lowers are cut from a larger, solid block of 6061 aluminum stock. They’re then machined into their final shape. Because billet lowers aren’t forged with a molding, they can “cut” into complex designs. They can also feature things like integrated trigger guards and threaded fittings more easily. Making a billet lower is more expensive, so retail cost is a little higher compared to a forged or billet lower.

A billet 80% lower receiver for an AR-15 build project.
Premium Black 80% Lower Billet Fire/Safe Engraved (1-Count)

Pros

  • Less wear on jig and tooling
  • Compatible with most jigs
  • Quicker to machine than forged
  • Features threaded fittings for easier assembly

Cons

  • More susceptible to machining mistakes
  • More expensive than forged or polymer
  • Softer than forged lower, more prone to scratching

Available Calibers:

  • 5.56/.223, .308, 9mm

Available finishes:

  • Raw
  • Type III Hardcoat Anodized (pictured)

Forged (7075 T6 aluminum, mil-spec)

Forged 80 lowers are made by pouring molten 7075 T6 aluminum into a mold. The lower is then pressed into its final shape using extreme heat and pressure. Forged lowers are less expensive to make, so they cost less than billet lowers. They’re also the most rugged and can take the most abuse. The U.S. Military uses forged receivers in their service-rifles for this reason.

A forged 80% lower used to build an AR-15.
Black 80% Lower Fire/Safe Engraved (1-Count)

Pros

  • Compatible with most jigs
  • The most popular choice for builders
  • More affordable than billet lower
  • More forgiving with minor machining mistakes
  • The most durable type of 80 lower receiver

Cons

  • No threaded fittings (traditional roll pins)
  • Exerts more wear on jig and tooling
  • Machining takes longer than billet
  • More assembly may be required (trigger guard)

Available Calibers:

  • 5.56/.223, .308

Available finishes:

  • Raw
  • Type III Hardcoat Anodized (pictured)

Nylon-Reinforced Polymer

The polymer lower is relatively new, but they’re the most affordable option. They’ve also proven their worth in the AR build game already. Polymer lowers are made of nylon-reinforced polymer, like a typical Glock or sub machinegun. This polymer was reinforced to safely handle supersonic rifle rounds (like .223, 5.56, and .308). Polymer lowers include a solid-core design to prevent cracking or failure. Hundreds of builders have used a polymer lower to build ultra-light AR-15s.

The polymer 80 Lower in Flat Dark Earth, used to build an AR-15.
Polymer 80 – AR-15 80% Lower Receiver and Jig Kit (FDE)

Pros

  • The most affordable 80 lower
  • Includes its own, proprietary jig
  • The easiest and quickest to machine
  • Includes its own 80 lower jig
  • Can be finished with hand tools

Cons

  • Most prone to scratches and surface wear
  • Less durable compared to billet and forged
  • The jig is usually sacrificed while machining

Available Calibers:

  • 5.56/.223, .308

Available finishes:

  • Natural (black)
  • Flat Dark Earth

Cast (A380 aluminum)

Cast lowers are technically a fourth available option, though we strongly recommend against using one to build your AR-15. Cast lowers are made by pouring A380 aluminum alloy into a mold. The lower is then left to harden into its final shape (no forging). This process can cause defects and imperfections. Cast lowers can contain hidden pockets, small cracks, or fissures. While machining or firing your AR with a cast lower, these imperfections could cause a catastrophic failure. The result is usually dangerous to the shooter and can result in injury or death.

cast-80-lower-receiver-blog-photo-#4
An example of a cast 80 lower. We don’t recommend building with one.

Pros

  • None

Cons

  • Can suffer poor build quality
  • May contain dangerous imperfections
  • Can crack or break while machining
  • Can cause catastrophic failure when fired

Available finishes:

  • Raw
  • Type III Hardcoat Anodized (pictured)

Minimum costs (with jig bundled)

The 80 lower jig is the other half of this project. You’ll be using one to complete your lower, turning it into a stripped AR-15 lower receiver. So, what’s the cheapest 80 lower you can grab with a jig? What’s the minimum cost for each, including buying an 80 lower jig and the tools you need? We already said the polymer option is the least expensive, so let’s review that before the others:

(AR-15) Polymer 80 Lower + Jig: $75

Polymer 80 – AR-15 80% Lower Receiver and Jig Kit (FDE)

Because the Polymer 80 lower comes with its own jig, it’s the most affordable option. If you want to buy your lower and tooling for under $100, this is the lower for you. The included jig is also made from polymer, so it’s likely the jig will be “used up” during the machining process. However, careful builders can salvage the jig for future polymer builds. Or, you can just get another jig with every polymer lower you buy.

Tools & parts included:

  • Polymer 80 Lower (5.56/.223)
  • Proprietary AR 15 Jig
  • Set screw bolt catch pin
  • Dowel pin for bolt catch
  • pistol grip nut
  • Pistol grip screw
  • Allen wrench
  • 7/16″ end mill Bit
  • 5/16″ drill bit
  • 3/8″ drill bit

(AR-10/LR-308) Polymer 80 .308 Lower + Jig: $95

An LR-08 80% lower with proprietary jig
Polymer 80 – LR-308 80% Lower Receiver and Jig Kit

If you were still unconvinced about the polymer lower’s durability, think again: It’s also available for LR-308 builds and is compatible with all DPMS Gen 1 components. It costs about $20 more than it’s 5.56/.223 cousin, making it the most affordable .308 lower-and-jig bundle you can currently buy:

Tools & parts included:

  • Polymer 80 Lower (.308)
  • Proprietary AR Jig
  • Set screw bolt catch pin
  • Dowel pin for bolt catch
  • pistol grip nut
  • Pistol grip screw
  • Allen wrench
  • 7/16″ end mill Bit
  • 5/16″ drill bit
  • 3/8″ drill bit
  • 5/32″ drill bit

(AR-15) Forged 80% Lower + Easy jig Gen 1: $250

A forged 80% lower with the Easy Jig Gen 1
Black 80% Lower Fire/Safe Engraved & Easy Jig Gen 1 with Tooling

The forged 80% lower bundled with the Easy Jig Gen 1 is the most affordable aluminum setup you can get your hands on. It comes in at around the $250 price point, and it includes everything you need to get the jig up and running. The Easy Jig is one of the most popular jigs on the market. Even though you’re paying the lowest price, you’re still getting one of the most popular options available.

Tools & parts included:

  • Forged 80 lower
  • Easy Jig Gen 1
  • 3/8″ drill bit
  • 3/8″ drill stop collar
  • 5/32″ drill bit
  • 19/64″ drill bit

(AR-15) Billet 80% Lower + Easy Jig Gen 1: $280

A billet 80% lower receiver with the Easy Jig Gen 1.
Premium Black 80% Lower Billet Fire/Safe Engraved & Easy Jig Gen 1 with Tooling

No surprise here – the cheapest billet 80 lower you can grab with a jig is bundled with the Easy Jig Gen 1 as well. The billet jig bundle is slightly more expensive (+$30) because of the higher cost of production for the lower itself. Nonetheless, you’re still getting everything you need to complete your lower:

Tools & parts included:

  • Forged 80 lower
  • Easy Jig Gen 1
  • 3/8″ drill bit
  • 3/8″ drill stop collar
  • 5/32″ drill bit
  • 19/64″ drill bit

Most Affordable Universal Jig (Easy Jig Gen 2): $300

The Easy Jig Gen 2 is compatible with the ar9, AR-15, and AR-10 80 percent lower receiver.
Easy Jig Gen 2 Multi Platform with Tooling (AR-9 / AR-15 / LR-308)

Maybe you don’t want to just buy the jig and lower you need. We get it. You’re probably going to build more than one 80% lower and different AR platforms anyway. So, here’s the most affordable universal jig you can grab right now, The Easy Jig Gen 2 Multi-Platform:

Features and specs:

  • Compatible with all 80% lowers (AR9, AR-10/LR-308, AR-15)
  • Includes necessary drill bits, end mill bit, and tooling
  • Completes most lowers in 15 minutes or less
  • Includes written instructions + video tutorial
  • 3/8″ drill bit
  • 5/32″ drill bit
  • 21/64″ drill bit
  • 5/16″ end mill bit

Additional tools required

You’ll have mostly everything you need to complete your lower once you’ve purchased a jig. But, there are some additional tools that you’ll need to actually drill and mill your lower to completion:

And lastly, you’ll need the core tool: A handheld router. Most jigs were built and tested using the Porter Cable Handheld Router. This little guy’s a crowd-favorite among AR-15 builders because it’s perfectly suited for machining aluminum. It features depth adjustments of 1/64″, perfect for making small, precise passes on your lower.

Specs and features:

  • 1.25-HP motor for plenty of power while machining
  • Real-time motor feedback maintains speed during cutting
  • Large 4″-diameter base for accepting 80 lower jig adapter plates
  • Depth ring and clamp to ensure motor remains locked in position

Summary

You should now be readily equipped to pick out the perfect 80 lower receiver! To recap, forged 80 lowers are the most popular and the least expensive, besides polymer. A polymer unit will be the cheapest 80 lower you can grab, especially considering it includes its own jig. Stick with forged, billet, or polymer lowers – avoid using a cast lower at all costs. They’re not safe. Most lowers can be bought with a jig to keep costs down, but the most affordable, universal jig is the Easy Jig Gen 2.

Now it’s time to build!


DISCLAIMER: If you are new to the world of DIY gun building, you likely have a lot of questions and rightfully so. It’s an area that has a lot of questions that, without the correct answers, could have some serious implications. At AR-15LowerReceivers, we are by no means providing this content on our website to serve as legal advice or legal counsel. We encourage each and every builder to perform their own research around their respective State laws as well as educating themselves on the Federal laws. When performing your own research, please be sure that you are getting your information from a reliable source.

DON’T MISS ANOTHER DEAL ON AR-15 GEAR

Get exclusive discounts on AR-15 gear and be the first to know about new product releases.

100% Satisfaction
Guaranteed

Customer Service is our passion and we are here to answer any questions you have.
317-426-6313

Shop With PRIDE

Shop With Confidence

Secure Payment

Left Menu IconMENU
Right Menu Icon