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Need to replace jig parts for your 80% project?

The drill bits and end mill bits that turn your 80% lower into a finished, precision-milled AR 15 receiver are the critical components of any 80 Lower Jig. Using dull, over-worked bits will produce a sub-par receiver that hangs triggers, sticks magazines and fails to fire consistently. Even worse, the milling process can result in some nasty injuries thanks to broken bits and flying debris.

Replacement 80% Jig Bits and Plates 

Generally speaking, a good set of bits can finish two 80% lowers. We strongly recommend investing in an extra mill bit for your first build, just in case – after all, you’re turning raw aluminum with steel at high rates of speed. Pressure, heat and speed can result in a broken bit and a halfway-finished lower sitting in a jig.

You never want to remove your lower from the jig once you’ve started machining, so having extra bits on hand will prevent issues like this. We only sell quality, made-in-the-USA hardware. Our 80 Lower Drill Bits and end mill bits are solid carbide steel and feature 0.75” flutes for performance and precision. 

You’ll also find we carry 3/8” bits, 5/32” bits, 19/64” bits and 3/8” drill stop collars – that includes everything you need to begin machining and finishing your own 80 Lower.


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.

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.