An 80% lower jig is the only way for an AR-15 builder to complete their 80 lower receiver with accurately drilled pin holes, and a properly milled fire control cavity for the trigger, hammer, and other components. Since, by design, an 80% lower still requires the builder to complete the last 20% of the milling process to make the receiver functional, an 80% jig removes the need for making complex calculations or programming a CNC machine.
Instead, the 80 percent lower jig provides pre-designed cutting and milling templates to be used in tandem with a drill press or mini-mill. Each jig also comes with "template" plates that provide guides holes for drilling the pin holes for the lower parts kit:
Our store carries both AR15 Jigs and AR-10 Jigs for 5.56 NATO and .308 Winchester builds. They are designed with safeguards in place so that you do not drill too deep or mill out more than necessary. Also included are the required drill bits for the pin holes, and end mill bits for cutting inside the receiver.
While the actual milling process takes some attention-to-detail, it is a fairly straightforward process and all our 80 lower jigs come complete with easy step-by-step instructions. Also, the individual components of each jig are clearly labeled for tooling and measurements and coordinate with the instructions to ensure your AR-15's finished receiver is a strong and sound success!
Some AR-type 80% jigs will work with all mil-spec, or forged, 80% lowers. Other jigs are made to fabricate just one type of 80% lower or 80% frame. Polymer80's frame jigs are made to fit a corresponding model of frame or lower.
Polymer jigs are made to be disposable, but they can be used more than once if you're careful when you machine. Aluminum 80% jigs are reusable, and can typically complete 2 to 4 80% lowers or frames.
Besides the jig, all you need is a drill press or mini-mill, a vise, and some machining oil. Our AR lower 80% jigs come with the required drill bits and end mill bits. Polymer80's pistol jigs may require hand files, a handheld drill, snips, or a Dremel to complete the corresponding 80% frame.
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, Hawaii, 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.