The M-16 Third Hole Drilling Jig is made for properly aligning and drilling the third hole for a full auto sear in an AR-15 style lower receiver. The drill hole is reinforced with a steel drill bushing to prevent wear and be able to use the jig over and over without any issues with tolerance. The jig and pins are made to exact tolerances. Be sure of proper fitment in your lower by reaming the rear take down pin hole to .250 and the safety selector hole to .375 which will ensure an accurate drilling of the 3rd hole.
We recommend fixturing and leveling the work piece horizontally in a vertical mill or drill press to ensure a straight hole through the lower.
The M-16 Drilling Jigs are proudly MADE IN THE USA.