What are the differences between billet vs forged lowers?

On your AR-15 journey you’ll likely find situations where you’ll be offered forged or billet lowers in your platforms. This is true if you’re building an AR-15 or buying one off the shelf. The billet vs forged debate really isn’t something we hear a lot about. We’ll dive into the differences and give you a better idea on its manufacturing process and what that might mean to you.

What is a lower receiver?

A lower receiver is the lower portion of the AR-15 (or AR-10). When you push out the takedown pins on a rifle, it’ll separate the rifle into two parts. The upper receiver and lower receiver. We’re discussing lower receivers today.

Read: Is the Aero Precision M5 Good?

The lower receiver can be in a few different states. A lower receiver can be stripped, partially complete, and complete.

Most people don’t call it partially complete – they’ll say it’s missing a part. Typically the missing part is the FCG (fire control group) or “trigger”.

What are the different states for lower receivers?


Receivers are a machined or forged piece of metal that does not have any parts installed

Read: What’s the best AR-15 stripped lower?

Partially complete

Receivers are a work in progress, typically missing a part from the full parts kit. You’ll usually see the FCG missing in these lower receivers.


All lower parts kit parts are installed along with a buffer, buffer spring, and buffer tube. It may or may not have a stock or brace on it.

How do I get a lower receiver?

To purchase a lower receiver, you’ll need to find one at your local FFL Dealer, an online gun dealer’s website, or a place like GunBroker. If you’re not purchasing from a local licensed gun dealer, you’ll need to have your lower shipped to a FFL (federal firearms license) dealer or “gun dealer”. These cannot ship direct to your home.

Your FFL dealer will know the local laws governing the purchase of a lower receiver.

What is a billet lower receiver?

A billet lower receiver is a receiver machined from a block of high grade aluminum alloy. The machining process mills the aluminum block with very tight tolerances. Some manufacturers are better than others of course – but in order for it to work properly – it must meet a minimum standard.

Machining on these lower receivers are totally dependent on the designer’s tastes and creativity. Spike’s Tactical has some beautifully designed billet lowers that will give your rifle a custom look.

How are billet lower receivers made?

These lower receivers are precision CNC machined to tight tolerances to deliver a fully functional and quality product. A small 1/1,000,000 off in either direction could cause malfunctions or make the rifle too “rattly” – as in the upper receiver and lower receiver don’t fit properly.

Because of the long cnc machining process, the skilled machinists running the machines, and the possibility for damages/rework – these stripped lowers are typically higher cost than the forged lowers.

What is a forged lower receiver?

Affordable forged lowers are forged through a hammering process from a block of high grade aluminum . Because of the forging process, forged lowers are typically lighter than billet lowers. They are also said to be much tougher than billet lowers.

Mil spec M16 and M4 platforms are usually made with a forged lower receiver.f

These are your standard lower receivers and can be found much more easily than the billet receivers. The billet lower will typically have an integrated handguard, whereas the forged lower will require a trigger guard.

How are forged lower receivers made?

The forged lower is made from a solid block of high grade aluminum alloy. It’s super heated and hammered into shape.

These are the most common lowers because they are mil spec – the military uses this type of lower in its M16 and M4 platforms.

We always suggest caution when building with a forged lower – installing the trigger guard can lead to damage of the lower.

Which lowers are better?

80% Arms described it best when they asked, which is better? As far as function – the lowers will both perform well. The billet lowers will usually cost more due to the the machinist use of the CNC machine.

Aero Precision sells both a forged and billet lower receiver. Here is their explanation of the two platforms.

But 80% Arms makes a great argument, do you buy steel ammunition because it’s $0.02/round cheaper than brass? Is it worth that much to you? The forged lower will be the most cost effective. However, we prefer using a billet lower to reduce the chance of breaking the trigger guard. If you’re confident in your skills – this shouldn’t be an issue.

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