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We are a national retailer of individual components and not all products depicted on this website are legal in every state. Shipping of various products found on this website are prohibited to some states (such as California, Connecticut, New Jersey, New York, Pennsylvania, and Washington). The information, pictures, text or products presented on this website are not a representation by us, and should not be understood by you, that any product or completed firearm is legal to assemble or own in your state of residence. We encourage each and every builder to perform their own research about the state and federal laws that apply to them. It is your responsibility to understand the law and we encourage you to consult with an attorney or your local ATF representative.

All 80% Lower Jigs Compared (Rifles and Pistols)

Posted by AR-15LowerReceivers.com on Jul 8th 2020

All 80% Lower Jigs Compared (Rifles and Pistols)

We've covered what 80% lowers are, and why you might want to invest in this option for building your first or next AR-15 or handgun. Now let's cover the various tools and equipment you need to consider to fabricate your new firearm at home. These tools are called 80% lower jigs, or 80% frame jigs, depending on the weapon you're making. This guide covers how they work for both rifles and pistols. With a basic understanding of their function, use this guide to review all the available 80% jigs to determine which jig you want or need to complete your chosen firearm.

Types of 80% Lower Jigs (AR-Type)

These jigs are used to build AR-type receivers, such as those for the AR-15, AR9, and LR-308, the commercial variant of the original AR-10 rifle.

1. Elite Builder Jig

The Elite Builder Jig is designed to be used with a drill press or milling machine. It's compatible with mil-spec (forged) and billet AR-15 and AR9 80% lowers. Since AR9 receivers use the same internals and components as the AR-15, the machining steps are the same. A larger version is available for .308 builds.

How it works

The Elite Builder provides two side plates for securing the 80% lower. A top plate holds four steel guides for drilling and milling out the fire control cavity, the area inside the receiver where you'll install your parts kit. One plate is used for drilling pilot holes, two plates are for milling the walls and floor of the receiver with the end mill bits, and the third is for cutting the trigger slot. The plates act as limits for the end mill bits, preventing you from cutting any part of the receiver that should otherwise remain solid. Once all four plates have been used to cut the fire control cavity, you'll need to secure the receiver and jig on its side to drill the pin holes for installing your parts kit. With all fabricating steps completed, the receiver will look like this:

What's included

  • (1) 3/8 Drill Bit - 5”
  • (1) 5/32 Drill Bit - 3”
  • (1) 3/8 Short End Mill - 3”
  • (1) 5/16 Short End Mill - 4”
  • (1) 3/8 Long End Mill - 4”

Tools required

  • Drill press or mill
  • Vise to clamp jig
  • Machining oil

Unique features

  • Made entirely from hardened, anodized steel
  • Provides drill bushings for accurate pin holes
  • Capable of completing 20 or more receivers

2. Polymer 80 Lower and Jig

The Polymer80 Jig is a combo kit, since it includes the 80% lower for your AR build. Unlike most jigs and lowers -- which are made from steel and aluminum, respectively -- this entire kit is made from nylon polymer. Nylon polymer is an incredibly tough plastic used most often in modern pistol-caliber carbines and handguns, and it works just as well for centerfire rifles chambered in 5.56 or .308, like the AR-15. A .308 version of this jig is available, too.

How it works

Like a conventional jig, the P80 polymer jig secures the 80% lower for drilling and cutting. Except instead of using various side plates and top templates, the jig is designed with all of these pieces in one. Because nylon-filled polymer is easy to cut precisely, the jig doesn't require heavy-duty template plates like those required for machining a billet or forged receiver. The included end mill bit is responsible for cutting the entire cavity, with a simple stop marker on the shaft of the bit to indicate how far down you must mill the receiver. Three drill bits are included, one for creating a pilot hole, and two for the pin holes. Written instructions and pictures providing greater detail can be found here.

What's included

  • (1) 3/8 Drill Bit
  • (1) 5/32 Drill Bit
  • (1) 23/64 End Mill

Tools required

  • Drill press
  • Vise to clamp jig

Unique features

  • Includes the 80% lower with the jig
  • The easiest-to-machine receiver and jig

3. JMT Polymer 80% Lower and Jig

Already own an end mill bit and the required drill bits for completing an 80% lower? The JMT Polymer 80% combo is probably your best choice. It combines the ease of machining of the Polymer80 kit with the template guide design of the Elite Builder jig, and it, too, includes an 80% lower. It does not come with either an end mill, nor the 3/8 and 5/16 drill bits required for the pin holes.

How it works

As with other AR-type jigs, the JMT unit secures the receiver between two side plates with a top plate bolting the assembly together. The top plate acts as one of the milling templates, with a polymer insert providing the templates for the rear shelf and trigger slot. First, you'll install the template with the "U"-shaped end facing the buffer tube. You'll cut to a depth of 0.63" in the rear shelf area, before removing the template and milling the rest of the cavity to a depth of 1.25". Lastly, you'll reinstall the template and cut through the floor of the receiver using the trigger slot guide hole. Detailed written and visual instructions can be found here.

What's included

  • 80% lower
  • Jig w/ template

Tools required

  • Drill press
  • Vise to clamp jig
  • (1) 3/8 Drill Bit
  • (1) 5/32 Drill Bit
  • (1) 5/16 End Mill

Unique features

  • Includes the 80% lower with the jig
  • The most affordable option for an 80% AR build
  • Template provides more precision than other polymer jigs

Types of 80% Pistol Jigs

When we say "pistol jigs" we're referring to 80% jigs made for handgun frames, not AR-type pistols. AR pistols use the same lower receivers as a rifle build, and instead swaps out a long barrel and buttstock for a shorter barrel and pistol brace. 

1. Stealth Arms Phantom 1911 Jig

With the 1911 platform receiving an aluminum 80% frame, the accompanying Stealth Arms Phantom Jig allows one to build a Government (5") or Commander (4.25") variant of the original 1911 with a lighter frame. Unlike AR-type jigs, no large power tools are required to complete your frame with the 1911 jig. the only power tool required is a handheld drill for completing the pin holes on the frame itself. Cutting the frame is also done by hand -- no mill, drill press, or other machinery required.

How it works

The 1911 jig consists of two large side plates that provide both the drilling templates for pin holes, and the cutting templates for the slide rails and barrel seat. A handheld, carbide-bladed "cutting car", similar to a wood planer in form and function, effectively slices away the excess aluminum on the frame to create the slide's and barrel's grooves. This process is done by incrementally adjusting the depth of the blades on the cutting car with an adjustment knob until the final required depth is reached. Then, the pin holes can be drilled with the provided drill bits. The process is surprisingly easy and requires no complex measuring or other calculations. The finished frame, although made from aluminum instead of steel, is compatible with all standard 1911 parts on the market.

What's included

  • Bladed cutting car
  • (1) #35 drill bit
  • (1) #22 drill bit
  • Lubricating oil

Tools required

  • Handheld drill
  • Vise

Unique features

  • Allows for fabricating an aluminum 1911 frame entirely by hand
  • Jig is reusable with carbide blades capable of cutting various frames
  • Can be used for completing either a 5" or 4.25" frame with one jig

2. GLOCK®-Compatible 80% Frame and Jig

The GLOCK®-compatible 80% frame and jig combo comprises a set of jigs and 80% frames, each designed to work with a particular series of GLOCK® handguns. Designed by Polymer80, these frames cannot legally be called "GLOCK® frames" but they're 100% compatible with all factory parts, including magazines.

  • PF940C is compatible with Glock® 19, G23, and G32 handguns.
  • PF940v2 is compatible with Glock® 17, G22, G24, G31, G34, and G35 handguns.
  • PF940SC is compatible with Glock® 26, and G27 handguns.

How it works

For this frame, very little cutting is required. Rather, the slide rails need to be trimmed flush with the rest of the frame. This can be accomplished with a simple pair of snips, followed by some hand files to de-bur the frame and ensure each rail is flush. Cutting the barrel seat requires a small Dremel, or for those who really want to take their time and make precise, incremental adjustments, a large round file can be used. All other procedures are the same: A handheld drill is used to drill the pin holes for the trigger mechanism and parts kit, and your frame is complete. Among all 80% frames and lowers, the GLOCK®-compatible kit is arguably the easiest firearm to fabricate.

What's included

  • M3 drill bit for trigger housing
  • M4 drill bit for trigger pin
  • Locking block rail system
  • Stainless ear rail module

Tools required

  • Snips or Dremel
  • Round and flat files
  • Handheld drill
  • Vise

Unique features

  • Allows for fabricating a a GLOCK®-compatible frame entirely by hand
  • Arguably the simplest and easiest-to-complete frame and jig combo
  • Works with all factory, aftermarket Gen 3 GLOCK® components

3. Sig Sauer P320 80% Pistol Kit and Jig

Just as Polymer80's GLOCK-compatible frames work with most of GLOCK's handgun platforms, the new Sig Sauer P320 and its various configurations now has an 80% frame -- or rather, an 80% "chassis" of sorts -- to allow for at-home builds. This is also the only 80% pistol jig that includes all the parts required for building a complete, functional handgun in one kit.

How it works

The 80% Sig Kit uses a stamped piece of steel called the MUP-1 80% Fire Control Unit, or FCU, to act as a universal internal frame, upon which all variants of the P320 can be built. We cover this particular project in great detail with this guide, but the summary is this: The Sig P320 uses one FCU to build four sizes (full, carry, compact, and subcompact) with four calibers available (9mm, .40 S&W, .357 SIG, and .45 ACP). Essentially, one fabricated 80% chassis nets you the ability to build a lot of different handguns. Like all other jigs and frames, this kit requires some cutting and drilling procedures to be made to the MUP-1 chassis, turning it into a firearm. You'll bend and trim the slide rails, cut the trigger slot, and drill plenty of pin holes.

What's included

  • 80% FCU jig with bits
  • 9mm slide (full or carry)
  • 9mm barrel with recoil spring
  • Grip module (full or carry)
  • Complete parts kit for FCU
  • Novak night sights
  • Carrying case

Tools required

  • Drill or drill press
  • Dremel with cut-off wheel
  • Machining oil

Unique features

  • The only jig kit that includes all components for building a firearm
  • One MUP-1 80% chassis affords compatibility with all P320 variants
  • Finished chassis compatible with four sizes and four different calibers

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 80-lower.com, 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.

We are a national retailer of individual components and not all products depicted on this website are legal in every state. Shipping of various products found on this website are prohibited to some states (such as California, Connecticut, District of Columbia, New Jersey, New York, Rhode Island, and Washington). The information, pictures, text or products presented on this website are not a representation by us, and should not be understood by you, that any product or completed firearm is legal to assemble or own in your state of residence. We encourage each and every builder to perform their own research about the state and federal laws that apply to them. It is your responsibility to understand the law and we encourage you to consult with an attorney or your local ATF representative.