How to Build a 1911 with an 80% Frame

Posted by 80-Lower on Jun 12th 2019

How to Build a 1911 with an 80% Frame

You want to own America's favorite handgun - congratulations! It's a smart decision. But do you want to buy some random piece off the gun store shelf? Risk having a mediocre .45 (or 9mm)? Nobody wants that, the 1911 is legendary. Today, we're showing you how to instead build John Moses Browning's greatest creation from scratch, using an 80% 1911 frame.

Building a 1911: The legal stuff

First thing's first: A lot of people ask, "can I build a gun at home?" The Bureau of Alcohol, Tobacco, and Firearms (ATF) has this say to on the subject:

“No, a license is not required to make a firearm solely for personal use. However, a license is required to manufacture firearms for sale or distribution. The law prohibits a person from assembling a non–sporting semiautomatic rifle or shotgun from 10 or more imported parts, as well as firearms that cannot be detected by metal detectors or x–ray machines. In addition, the making of an NFA firearm requires a tax payment and advance approval by ATF.”

[18 U.S.C. 922(o), (p) and (r); 26 U.S.C. 5822; 27 CFR 478.39, 479.62 and 479.105]

The 1911 is not:

  • A shotgun
  • An NFA gun
  • A non-sporting semiautomatic rifle
  • A gun built with 10 or more imported parts
  • A gun that can’t be detected by metal detectors or X-rays

We’re not building our 1911 to sell it, and we have no intentions of doing so. So, we’re in the clear as far as Federal law is concerned.

State laws

Some states have special restrictions against building guns at home, especially handguns. California, for example, only allows specific handgun makes and models that have been tested for certain safety requirements to be legally owned in the state. Unfortunately, that excludes the 1911 frame blank. Check your local and state laws before building. Moving on, let's look what what parts we need:

Finishing a 1911 80% Frame: Parts Needed

A .45-ACP, 5-inch Tactical 1911 Build Kit This Build Kit features a 5", .45-ACP 1911 with a raw finish and Picatinny rail.

Here’s what you’ll need to build your gun from scratch. The first two components of the project, the frame blank and parts kit, are caliber- and frame-specific and must correspond with each other.

For example, if you want to build a classic, G.I.-style gun chambered in .45 APC, you’ll need a 5” Government frame blank and 5” Government Parts Kit. The same rules apply for Commander and Officer models, as well as variants chambered in 9mm or .38.

"Are these 80% 1911s compatible with retail parts?"

Yes. If you wanted, you could just buy a frame and jig, complete the frame, and then buy all the parts you'd need from wherever else. But the parts kits, barrels, and slides included with the frame blanks are specifically machined to ensure tolerances are perfect for final assembly. If this is your first time owning or building a 1911, we recommend purchasing the parts included with the full build kit.

Frame blank vs. Retail frame

Speaking of aluminum, the 1911's 80% frame is not made out of steel. Instead, these blanks are made from forged, mil-spec aluminum. This is no different than using a typical 80% lower used to build an AR-15. This aluminum construction provides some big advantages, the biggest being weight savings. The aluminum frame weighs around 60% less than a store-bought, steel frame. That's a huge reduction in weight, making the finished gun more comfortable and ergonomic without sacrificing reliability.

And since the frame blank isn’t a firearm, it can be bought, sold, and shipped to you without having to deal with the ATF or an FFL. Nothing else you’ll buy for this project is considered a firearm either, including the parts kit and jig.

Cutting and Drilling the Frame Blank

Now that we’ve cleared up the legal stuff and figured what you what you need for the build, let’s get started! These instructions are to be used only with the Phantom 1911 Jig by Stealth Arms. Other 1911 jigs may work differently:

Step 1: Insert 1911 frame into Phantom Jig

Phantom Jig Instructions, Step 1: Insert 1911 frame into Phantom Jig

The Phantom Jig secures your frame blank using two provided dowel pins and one Allen-head set screw. Seat the dowel pins into one of the two plates as pictured. Let your frame slide onto the dowel pins and then sandwich the frame using the other plate and set screw.

Step 2: Drill the hammer and sear pin holes

Phantom Jig Instructions, Step 2: Drill the hammer and sear pin holes

Rest your frame and jig on its side. Secure the larger drill bit (pictured #22) into your drill and drill half-way through the frame to begin making the hammer pin hole. Repeat drilling of the sear pin hole using the smaller drill bit (pictured #35). Then flip the frame and jig and finish drilling on the opposite side.

WARNING: Don’t attempt to drill all the way through the frame on one side. Your drill bits will hit the surface underneath the jig and cause your drill to “walk”, damaging your frame and work bench.

Step 3: Set up the cutting car

Phantom Jig Instructions, Step 3: Set up the cutting car

After drilling both holes, you’ll move on to the cutting car. This is the manual cutter used to finish the slide rails and barrel seat. The car already has the slide rail and barrel seat cutting blades installed, but they need to set before you begin cutting.

Loosen the Allen-head set screw securing the slide rail cutter (pictured), and carefully push the blade up into the car so the blade’s edge is slightly inside the bottom of the opening. Re-tighten the screw.

Phantom Jig 80% 1911 Instructions, Step 3: Setting the blade and adjustment knob.

Next, thread the cutting handle and adjustment knob atop the car (like shown). You’re now ready to find your starting point for cutting.

Step 4: Set up the jig for cutting

Phantom Jig 80% 1911 Instructions, Step 4: Set up the jig for cutting

Place the provided spacer block inside the center of the slide rail slot on the guide plate (pictured).

Then, secure your frame and jig in a tabletop vise as shown.

Step 5: Set the initial cutting depth

Phantom Jig 80% 1911 Instructions, Step 5: Set the initial cutting depth

Once the jig and frame are secured, grab the included machining lubricant and apply some to the frame, inside the slide rail slot on the guide plate. Next, rest the cutting car atop the frame, with the cutting blade resting inside the slide rail guide slot.

Gently move the cutting car back and forth atop the frame while turning the adjustment knob clockwise. This will begin bringing the cutting blade in contact with the frame. Continue rotating the knob until the blade contacts the frame. This is your initial cutting depth.

Once you’ve found the initial depth, grab a marker and mark where the adjustment knob is in relation to the jig (pictured).

Step 6: Measuring slide rail cutting depth

Phantom Jig 80% 1911 Instructions, Step 6: Measuring slide rail cutting depth

There are notches surrounding the adjustment knob. These notches represent 1/10 th of a full revolution of the knob. The knob must be rotated 19 times (1.9 complete revolutions) to achieve the desired cutting depth of 0.61”.

Step 7: Cut the slide rails

Phantom 1911 Jig Instructions, Step 7: Cut the slide rails

Once you’ve found and marked the starting position, begin cutting the slide rails by pushing the car forward across the frame. Make 3 to 4 passes before rotating the adjustment knob one notch. After making a forward cutting pass, it’s a good idea to lift slightly on the cutting car in order to bring it back to you for the next pass.

This will prevent the back of the blade from dragging along the frame and dulling. Be sure to clean out metal scraps and debris while you cut. It’s also important to occasionally apply machining lubricant/oil while you cut.

Repeat for the opposite side.

Step 8: Set up the jig for the barrel seat cut

Phantom Jig 80% 1911 Instructions, Step 8: Set up the jig for the barrel seat cut

Once both slide rails have been cut to 0.061”, disassemble the frame and jig and re-position the dowels pins in the side plate as shown. Re-secure the frame and jig atop the guide pins, and re-seat the jig with the provided set screw (pictured).

Step 9: Secure the jig for cutting again

Phantom Jig Instructions, Step 9: Secure the jig for cutting again

Secure the frame and jig vertically in a tabletop vise, like shown. The barrel end of the frame should face toward you.

Step 10: Set up the cutting car for the barrel seat

Phantom Jig Instructions, Step 10: Set up the cutting car for the barrel seat

Loosen the adjustment knob and handle on the cutting car. Re-position both on the left-hand side of the car as shown. Repeat step 5 to find the initial barrel seat cutting depth.

Step 11: Cut the barrel seat

Phantom Jig Instructions, Step 11: Cut the barrel seat

Repeat step 7 and cut the barrel seat to a depth of 0.077”. This is achieved by making 2.4 complete rotations of the adjustment knob, or 24 notches. Mark the starting position and make 3 to 4 passes, lifting and lubricating as needed until cutting is complete.

Your 80% 1911 frame is complete!

Once you’ve finished cutting the barrel seat, you’ll be the proud owner of a real, functional 1911 frame. At this point, you’re now the owner of a firearm in the eyes of the ATF. And now, you must observe all applicable gun laws. But now comes the fun part: Finishing your 1911 and hitting the range. All you need to do now is install your 1911's parts kit, which includes the barrel and slide.

Install your 1911 Parts KitA 9mm, 4.25-inch Commander 1911 parts kit.

Like we said, your completed 80% 1911 frame functions exactly like a retail or store-bought 1911. The parts kit installation is just like any other 1911 you've put your hands on.

If you're not familiar with the installation procedures, there are plenty of resources online (trying to provide every step and photograph in this guide would be unfeasible). One of our customers, Sterling Archer, created a wonderfully paced, easy-to-follow instructional video. Check it out here if you need detailed instructions to complete your installation.


Equipped with our guide, you should be able to master your 1911 build and create the perfect G.I. or compact shooter. If you have any questions about purchasing or finishing a frame blank, using the Stealth Arms jig, or assembling your parts kit, just give us a call or email us. We build our own guns, too! We're glad to help.

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, 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.