I don't even go to that trouble. All I do is take the field blade off of the one I want grounded, remove the insulating washers and screw it back down. Grounded.
That’s how old school I am I guess. I don’t even like doing it that way, I usually get the newer style VR and plug and just splice it in. But, I’ve done the pigtail many times too! This old dog is hard to train new tricks, just me I guess.