AR15 80% Lower Milling Upright Jig for Drill Press

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A friend requested assistance in creating a support system to simplify the process of finishing AR15 80% lowers on his drill press. He was using a method involving a vise block placed in the magwell, specifically designed for this purpose, and then clamping it down in a milling vise. Although this worked adequately, he needed to closely monitor angles to prevent movement. He asked me to design something with a longer base that could be bolted to both the jig and the vise itself, which is not a clamping vise. He intended to use his Proxxon vise, so I designed it to fit the clamping rails on this vise. This design is tailored for lowers with removable trigger guards. I decided against pre-drilling holes, instead recommending that you carefully drill through them to accommodate pins or screws for better hold. The jig tightly fits the lower and may require slight rounding of the magwell edges depending on the cut of the lower. When using this support system, avoid excessive heat during milling to prevent warping due to material expansion. To eliminate play from the process, the Proxxon vise will be bolted to a drill press, which I plan to post separately for mounting on a Craftsman drill press, though it may work with others as well.