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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.

80% Lower Jigs Compared

Posted by 80 Lower Jig, Co. on Jul 28th 2020

80% Lower Jigs Compared

You know what an 80% lower is (and if you don't, start here) and now you're curious about the mechanics of completing your own firearm at, from scratch. The 80% jig is the tool you need to get the job done. What jigs are available that let you easily fabricate a lower (or frame for a pistol) and how do they stack up against each other? We're comparing all jigs today, including combo kits which provide the jig and frame or lower, proprietary to one another.


Rifle and AR-Type Jigs

We're covering the classic stuff first with jigs made for the original 80% lower receiver, developed for the AR-15 platform. This single rifle has ballooned to cover news calibers, configurations, and types of AR patterns. That means new types of 80% lowers and jigs.

Elite Builder Jig (Drill Press/Mill)

Receiver Compatibility: AR-15, LR-308, AR9 (aluminum or polymer)

The Elite Builder, made for AR-15 and AR9 lowers, is one of the simplest yet reliable jigs available for the AR platform. It also sticks to the most proven method of machining: Milling the fire control cavity. In providing a platform for proper milling, the EB Jig effectively replicates the same machining procedures large rifle manufacturers employ to shape their lower receivers. The jig is made from a collection of aluminum and steel plates, with high-speed steel (HSS) bits provided for milling and drilling your 80% lower. Because the jig indexes the receiver via the pivot and takedown pin holes, it's capable of completing an AR-15 or AR9 lower of virtually any shape. A larger version of the EB Jig is designed to complete an LR-308 or AR-10 80% lower receiver. This jig is capable of completing multiple receivers.

Tools Required

  • Drill press or milling machine
  • Lubricant / machining oil
  • Vise

Who's this jig for?

If you want the traditional setup for completing the typical forged or billet AR-15 80% lowers, the Elite Builder is the jig for you. It uses conventional power tools many builders and machinist-minded gun owners already own, like a drill press or mini-mill.

Polymer RJ556U Jig (Drill PRess/Mill)

Receiver Compatibility: Mil-spec AR-15 (aluminum or polymer)

The RJ556U Jig is designed to be a simple-to-use, disposable variant to a resuable drill press or milling jig like the Elite Builder. For the one-off builder who wants to keep his 80% build as affordable as possible, the RJ556U provides a decent cost savings compared to reusable jigs. It provides the same type of form and function: It uses side plates and various template plates  with end mill bits to guide you along as you cut and drill the receiver. Its polymer construction means this jig is disposable, though with care, it may be reusable for a second receiver. Because of its design, this jig is only compatible with mil-spec 80% lowers and will not interface with custom billet receivers that use different external shapes or dimensions.

Tools Required

  • Drill press or milling machine
  • Lubricant / machining oil

Who's this jig for?

Since the RJ556U cost around $50, this affordable jig is for the builder who wants the lowest costs when building their AR from a typical forged or billet 80% lower using conventional tooling.

JMT Polymer 80% Jig w/ Lower

Receiver Compatibility: AR-15, AR-10 or LR-308 (Polymer, JMT Brand)

If you're opting for the easiest-to-complete 80% lower and want an affordable jig like the RJ556U, the JMT Polymer Kit offers both in one package. With a proprietary polymer lower included with its polymer jig, the JMT combo kit provides a disposable tool kit with a receiver that's much easier to cut and drill than an aluminum lower. Because polymer is less dense and hard, it can be quickly and safely milled with a drill press, making machining easier for the builder with basic tools. This jig also includes the required bits for completing the receiver. Besides its polymer construction, the JMT 80% lower provides the same form and function as an aluminum lower, utilizing the same lower parts kit and buffer tube as a mil-spec receiver. Its mag well is designed with Magpul's PMAG pattern for an aesthetic bonus.

Tools Required

  • Drill press
  • Vise

Who's this jig for?

At around the $80 price point, the JMT lower-and-jig set is for builders who want an affordable and disposable jig, while also enjoying the benefits of completing a low-cost and easy-to-machine polymer 80% lower for their AR build.

Polymer80 80% Lower & Jig

Receiver Compatibility: AR-15 (Polymer, P80 Brand)

Polymer80 provides yet another alternative to the conventional aluminum lower route by offering their take on a proprietary combo kit. Their jig functions like JMT's, providing the tools and guides to cut and drill their included polymer 80% receiver. This receiver is also considered mil-spec, working with any standard AR-15 parts kit, buffer tube, magazine, and all other typical AR accessories. And like JMT, this polymer unit can be easily milled with a drill press and the included end mill, making cutting and drilling easy for first-time builders.

Tools Required

  • Drill press
  • Vise

Who's this jig for?

At around the $100 price point, the P80 lower and jig are a simple alternative to JMT's option, adding around $20 in cost for a receiver that more closely looks like a conventional aluminum "mil-spec" receiver.


Pistol 80% Jigs

These jigs provide the templates and tools for building an 80% pistol or handgun, just like you may have done (or are considering doing) for an AR build. Options are currently available for machining an 80% frame for GLOCK's series of handguns, Sig Sauer's P320 modular handgun, and the 1911 in both Government and Commander profiles.

Phantom 1911 Jig by Stealth Arms

Frame Compatibility: 80% 1911 Builds (Aluminum)

Stealth Arms' Phantom Jig is made for cutting and drilling the company's billet aluminum 1911 80% frames. Unlike AR-type jigs, this tool kit doesn't require any drill press or fixed machine. You can complete your frame using nothing more than a hand drill. Cutting the frame's barrel seat and slide rails is completed using a handheld cutting car. The cutting car functions like a wood planer, shaving off layers of aluminum until the appropriate cutting depth is achieved. Unlike the original 1911's steel frame, these aluminum frames weigh approximately 50% less and provide the same functionality and parts compatibility with all "retail" 1911 brands and parts. 

Tools Required

  • Black marker
  • Electric drill

Who's this jig for?

With the 80% frame included, the Phantom Jig kit runs around the $350 to $400 price point, depending on the type of frame included (coated or raw, with or without a rail). Because no expensive tools or machines are required, fabricating  a frame for a custom 1911 may be the more affordable alternative to buying a branded pistol. 

Polymer80 GLOCK-Compatible Jig

Frame Compatibility: 80% GLOCK®Builds (Polymer80 Brand)

GLOCKs are to the handgun world what ARs are to the black rifle world: Easy-to-customize, modular shooters that make great platforms for building custom weapons. The GLOCK® received the 80% treatment via Polymer80's frames, allowing builders to fabricate the firearm component for almost any GLOCK® series. Completing one of these frames is easy and doesn't require a drill press or fixed machine. Cutting the slide rails and barrel seat is accomplished with a Dremel or snips and hand files. The holes to be drilled into the frame are completed with an electric drill, and the kit includes the required drill bits. To facilitate install of your parts kit, a custom stainless steel locking block and rear rail module are included for interfacing with the trigger mechanism and slide. P80's three available frames and jigs are compatible with the following handguns:

  • PF940C is compatible with G19, G23, and G32
  • PF940v2 is compatible with G17, G22, G24, G31, G34, and G35
  • PF940SC is compatible with G26, G27

Tools Required

  • Electric drill
  • Dremel or snips
  • Sandpaper for fitting

Who's this jig for?

These frame and jig kits are for anyone who wants to build a custom GLOCK® without spending extra on branded components, and without having to pay a premium to own a stamped and serialized Austrian frame. Besides the branding, P80's frames are identical in form and function to a GLOCK® frame.

Sig Sauer P320 Jig & 80% Firearm by JSD

It may not look like much until assembled, but the Sig Sauer P320's 80% option includes the stamped-steel fire control unit (FCU), which is the firearm component of the weapon, the jig to cut and drill the FCU, and the parts kit for making the FCU into a functional firearm that can accept a slide, frame, barrel, and magazine. Since the P320's FCU is universal, you only need one jig, one FCU, and one parts kit to build all available P320 handguns. The P320 is available as a full-size, carry, compact, and subcompact pistol chambered in .357 SIG, .40 S&W, 9mm, and .45 ACP.

Tools Required

  • Dremel
  • Drill press
  • Cut-off wheel
  • Rubber mallet

Who's this jig for?

These frame and jig kits are for anyone who wants to build a custom GLOCK® without spending extra on branded components, and without having to pay a premium to own a stamped and serialized Austrian frame. Besides the branding, P80's frames are identical in form and function to a GLOCK® frame.


More on Tools and Parts Required

That wraps up coverage of the common and popular 80% jigs and their corresponding receivers, frames, and weapon platforms. Before diving into machining your first or next build, consider reviewing the required and recommended tools you should invest in to truly make cutting and drilling your 80% lowers and frames as easy as possible.

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.