Our tool of choice for removing these nuts was a Vaco 9/16 nut driver, filed down for sharp edges, then center drilled for enough depth for the bnc connector, then thin tape added to the face just filed down. I only used the same one for about 25 yrs. at HP/Agilent, then another at NGC for 11 yrs. Never an issue, no scratches. You can also use a 9/16 6 point box wrench with a taped side in some places.
Don Bitters
