The jig is a necessary piece of gear to finishing your 80 lower. An 80 lower jig acts as a template when you start milling your lower receiver. Without it, you are drilling and milling in the wind. Using one properly is the key to successfully finishing your 80 lower. A good jig will be a solid piece of gear, no paper or sticker jigs. A heavy duty jig can finish well over a dozen different lowers. The key to using one successfully is to know how to use it, and a few helpful tips will make things a lot easier.
Our Top Tips & Tricks
1. Inspect the 80 Lower Jig - Before you begin milling out or even attaching your 80 lower jig to your 80 percent lower receiver, give it a good once over. Wipe any grease or oils off of it. Ensure the jig is in good working order. Jigs are meant to be replaced, so if this jig has been used before this is critical.
2. Tightening the Bolts - When tightening the bolts, you want to tighten them in an alternating manner. This advice applies to both sides, as well as the top block. A slight twist is all it takes and move to the next bolt. Repeat the process until the jig is tightened down. This guarantees the jig is tightened evenly over the receiver. If it is not tightened evenly it may slip. Even a small slip can ruin a cut.
Do not over-tighten the bolts. Tighten until the 80 lower jig firmly holds the receiver in place. Over-tightening may strip the bolts, or more importantly may scratch the finish on your lower receiver.
3. Masking Tape - Masking tape should be applied to any areas that are exposed and are not being milled. This masking tape should not get between the receiver and jig. This can make an uneven fit between the jig and the receiver.
4. Watch for Chips - When you start milling, metal chips will be flying out of the receiver. Because of this you must do two things. First, wear safety glasses. Safety glasses will guarantee you don’t lose an eye or two. Second, you want to make sure chips don’t start building up on the jig or between the jig and receiver. The chips will probably be hot and can melt to the jig, or receiver. So clean and wipe them off when possible.
5. A Good Vise - A good vise is worth its weight in gold. This will hold your 80 lower jig and receiver stable as you drill and mill. The vise either needs a rubber pad, or you can add a section of leather to keep the vise from damaging anything. Do not over-tighten the vise either.
Whenever you start milling, remember to take some basic safety precautions. This includes eye and eye protection. We would also work in a dedicated shop versus your kitchen or anything like that. A good workspace with good lighting is a blessing.
A solid set of instructions can be a lifesaver. One of the best manuals we’ve ever seen is here: https://cdn.shopify.com/s/files/1/0020/5370/1690/files/Easy_Jig_Gen_1_Instructions.pdf
Check at our selection of 80 Lower Jigs here: https://www.ar-15lowerreceivers.com/collections/80-lower-jigDISCLAIMER: If you are new to the world of DIY AR-15 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. 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.