What is the Best Drill Bits for 80% Lower?

Best Drill Bit for 80% Lower

A drill press is one of the most important tools for finishing 80% lower. However, you’ll need other tools as well including the best drill bits for 80% lower.

One thing you need to remember though is that drilling on AR lower is quite different from working with other materials. For that, not every drill bit set out there will machine your 80% lowers with efficiency.

Besides, drill bits are made up of different materials and come in various sizes. On the same note, these tools are designed to perform different tasks. Therefore, it is easy to end up with the wrong drill bit set for machining your 80% lower.

Fortunately, this article will help you avoid that. Thanks to our comprehensive review of the best drill bit set worth buying for drilling holes into your AR lower. First, let’s check out the ideal drill bit sizes for this project!

What’s the best drill bit size for drilling 80% lower?

As said earlier, drill bits are available in many sizes to create various types of in different materials. The same case applies to the best drill bits for AR lower. On the bright side, all AR’s calibers utilize the same pinhole diameters and part kits.

For that reason, the bits needed for chewing through AR lowers are universal. More importantly, you may want more than one drill bit size, especially if you’re planning to drill holes of various diameters.

With that in mind, you’ll need the following drill bit sizes when working on 80% lower;

  • 3/8” drill bit. Used to drill the safety selector lever pinhole and mill the pilot hole.
  • 5/32” drill bit. Used to drill the pin holes for the disconnector/ trigger and hammer.
  • 5/16” long end mill. Used to cut the trigger slot in the receiver’s floor.
  • 3/8” long end mill. Used to mill the main cavity for installing the parts kit.
  • 3/8” short end mill. Used to mill the receiver’s rear shelf portion.

Note, you can use any diameter end mill to mill the main cavity. Moreover, the 3/8” end mill works well with drill presses and delivers a clean cut.

Now, let’s move on to the best drill bit sets for 80% lower reviews!

3 Best Drill Bits for 80 Lower



First on the list is this set of 4 flute end mills from AUTOTOOLHOME. The bits have a U-shaped groove design and a large front angle to reduce cutting resistance.

More notably, they’re durable and sharp to enhance their machining efficiency and ensure convenient chip removal.

Surprisingly, those are not the only features that make this set the best drill bits for 80% lower!

Instead, this AR drill bit set has many stand-out features including a durable HSS construction. On top of that, these drill bits are hard and include a TIAIN coating.

For this reason, they’re suitable for processing heat-treated materials under 32 degrees with high speed. At the same time, this enhances their production efficiency, while reducing the changing times.

Still, on construction, these drill bits are crafted from superior Ultra-fine tungsten steel bar which is highly flexible. As a result, they’re highly resistant to abrasion and bending.

When it comes to application, these drill bits are ideal for various uses. To start, they work well on aluminum, which is the commonly used material in AR lowers.

However, you can use it on other materials like cast iron, die steel, titanium, alloy steel, and carbon steel. On the same note, it’s ideal for finishing, side milling as well as end milling applications.

As for the sizes, these drill bits come in various diameters to suit the needs of your 80% lower finishing project. They include; 1/16”, 5/32”, ½”. 3/8”, 5/16”, ¼”, 3/16”, and 1/8”.

Lastly, these end mills have a rounded chamfer design with a straight shank handle. This improves work efficiency and makes them easy to install into drill presses, milling machines, and so on.


  • 4 flutes form design
  • Works on several types of materials
  • Made of HSS construction with TIAIN coating
  • High cutting hardness
  • Resists abrasion and bending


  • No carrying case

2. SPEED TIGER ISE Square End Mill for AR Lower

SPEED TIGER ISE Square End Mill for AR Lower

SPEED Tiger is a Taiwan-based manufacturer of precise carbide cutting tools that have been around for over 2O years now.

Their cutting tools are crafted at high nanometer precision, giving users professional cutting quality. Well, their ISE square end mill for 80% lower is no exception!

Like any other square end/ flat end mill, this cutting tool has sharp corners and generates a 90-degree angle. More notably, it has a high feed U-type design, making it ideal for copper alloy or aluminum application.

Besides, its tooth has a sharp aluminum alloy design to ensure a smooth application for finishing and roughing 80% lower.

Moving on to construction, this cutting tool is crafted from Micro Grain Carbide material. For this reason, it’s very tough, wear-resistant, and delivers high cutting performance.

In addition, it’s coated with AlTiBN (Titanium Aluminum Boron Nitride). This coating gives it exceptional wear resistance, especially at high cutting speeds.

More importantly, it lubricates the tool during use, allowing it to withstand extremely high temperatures. Besides, AlTiBN coating is known to provide better high temperatures resistance than TiCN, TiAIN, and TiN coatings.

On the downside, this product only comes with one piece of 3/8” drill bit size. Other than that, it has an effective rate of chip removal, particularly when working on AR lowers, thanks to the 4 flutes.

Also, it’s suitable for use on various materials including hardened steel, alloy steels, carbon steels, and cast iron.


  • Outstanding heat resistance
  • High cutting performance
  • The effective rate of chip removal
  • Works on various materials
  • Crafted from solid Micro Grain carbide


  • Available in one drill bit size only

3. Wokesi End Mill Bits

Wokesi End Mill Bits

Available in a set of 7 end mills, this tool from Wokesi is another great option for drilling and finishing AR lowers. To be precise, the included end mill sizes are; ½”, 3/8”, 5/16, ¼”, 3/16”, 5/32”, and 1/8”.

Therefore, you’ll easily get the ideal size for your 80% lower finishing project based on your needs.

Besides, this AR 15 80 lower drill bit set has cutting teeth on the sides and at one end. For that, they cut through AR lower in all directions. More notably, this makes them ideal for various applications including cutting channels or slots and finishing an edge.

On top of that, these cutting tools are suitable for use in several materials. As an example, they work well on aluminum, wood, plastic, cast iron, magnesium alloy, and cast iron.

In terms of design, these square end mill bits have 4 flutes. This allows them to provide a better finish as compared to other drill bits needed for 80% lower with fewer flutes.

As if that’s not enough, the cutters are full grinded to deliver a fine finish and more accuracy than other cutting tools.

Moreover, each bit is made of HSS (High-Speed Steel), giving it incredible strength to handle aggressive work. Even better, this gives them high abrasion resistance and extends their life.

All things considered, this 7-piece end mill cutter will make a great cutting tool for your AR lower finishing project.


  • Includes 7 different sizes
  • Provides a better finish than bits with fewer flutes
  • Ideal for finish machining, end milling, and side milling
  • Designed for high-speed cutting projects
  • High abrasion resistance
  • Made of super-strong HSS (High-Speed steel)


  • Hard to identify different sizes


80% Lower allows you to easily build the perfect AR to suit your needs. And provided you’ve got the right tools including the best drill bits for 80% lower, that task will be fairly simple.

Hopefully, choosing the best drill bit for 80% lower for your project will not be difficult after going through our reviews. Besides, our list has included the pros and cons of each tool to help you make the best buying decision.

Up Next: Best router for finishing 80 lower

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