What is the appropriate way to bond a metal junction box containing a receptacle wired with 6 AWG wire? It seems that most metal junction boxes have a 10-32 tapped hole to accept a ground screw but almost all of the pre-built pigtails that I've seen that attach to this screw are 12 AWG. Using some sort of ginormous wire nut to connect 2-6 and 1-12 AWG wires doesn't seem like the right move.
Is there some sort of ground lug that attaches to the 10-32 hold and then accepts the two 6 gauge wires? How is this normally done?