Rupes lhr21 mark2 washer modification?

[Indiglofish61]

I have read the post on the washer mod, I have the 5/16 washer that you can grind down as in the video I have seen, and the 7mm, and the 8m, I have not the rupes polisher yet, but what really is the w best washer to use

 

[Indiglofish61]

Excuse extra w on my post, thank you.