Garbage for metal lowers - Polymer80 P80RJ556U Mil-Spec AR15 Lower Universal Jig Polymer

Absolutely no way to use this properly to mill a metal lower reciever. The jig flexes way too much even in a good vice. May work for polymer lowers I'm not sure but it flexed way too much to be used with a metal lower. The bits did seem to cut through the metal just fine. The only failing point was the flexing of the jig to the point where you can not get a straight wall inside the trigger hole