By far the most superior method of bench bleeding a master cylinder for us has been by reverse injection, pushing fluid into the brake line ports, which then VERY conclusively pushes all of the air up and out of the MC pistons:
https://www.youtube.com/watch?v=FB8k...ature=emb_logo
https://www.cardone.com/catalog/brak...r-bleeder-tool
https://www.summitracing.com/parts/AAZ-10-5000MCB
This is the secret to keeping your sanity LOL
