Depending on where you live (and other legal factors) you may be able to create a functioning firearm at home for personal use, with a build kit and an 80% receiver, also known as a receiver blank.
Unfinished receiver blanks cannot be used to create functional firearms in a firing state and must be milled and finished before the entire platform can be assembled. To streamline this process and ensure precise workmanship, most people who undertake such projects use 80 percent lower jigs.
What Is an 80 Percent Lower Jig?
An 80 percent lower jig is sort of like a workstation or a small template, often made of metal or polymer. The jig itself consists of metal plates and guides that show you where you need to mill and how deeply, so you can complete the fire control cavity and finished holes.
A jig kit typically contains side plates that secure the receiver blank during the process of milling the holes necessary to complete it. The side plates also contain guides for drilling so you can install the pins for the fire selector lever, trigger, hammer, and disconnector.
An 80 percent lower receiver jig kit also typically contains a top plate and pilot hole template plate, as well as fire control cavity (FCC) templates, as well as a trigger pocket cutting template so the trigger group can be installed into the lower receiver.
Together, the jig or jig kit can serve as a collective template that can be used with a vise, drill press, and necessary drill bits to mill out the receiver so it can be used to complete a functioning firearm.
What Should You Look for?
Not all 80 percent lower jigs are created equal. Before you buy a jig kit, make sure:
-The jig kit is compatible with the receiver blank you have. There are universal jig kits you can buy that contain all the plates needed to create AR-15s, AR-9s, and AR-10s.
-Look for an integrated vacuum attachment to remove metal swarf to keep your drilling channels (and your jig) clear of debris.
-Choose a jig kit with integrated depth gauges that are clearly marked.
-That the jig assembles quickly and easily.
-To ensure the quality of the jig construction. Jigs made from hardened, heat-treated steel will stand up to repeated use.
If You’re Going to Purchase a Polymer Jig…
Not all 80% lower jigs are made from steel. Some jigs on the market may be made from polymer which is commonly used for 80% pistol lowers such as the GST-9.
If you’re thinking of obtaining a polymer jig, visit 5DTactical.com and purchase a jig such as the GST-9 Polymer Jig that is specifically engineered for enhanced performance.
It is made with an advanced, stronger glass-filled polymer compound for added durability and diminished flexibility. It also features enhanced drill guides and 5 polymer bolts that will shear instead of ruining the jig, in the event, they are accidentally overtightened. This unique polymer jig is designed to eliminate common concerns with polymer jigs so that you’ll never experience the disappointment of accidentally running a receiver blank.
Contact 5D Tactical
To learn more about this or their other 80 percent lower jig kits, visit 5DTactical.com or contact their customer service directly at 508-834-4223 or at sales@5DTactical.com.
*Nothing in this post can be construed as legal advice. Before purchasing any parts or beginning a project, be sure to perform your own research about the state and federal laws that apply to you. Contact a lawyer or a local ATF representative to ensure that you will be in compliance with all applicable laws and regulations.