I need to countersink a 5/16 inch machine screw into 3/8 inch T6. The diameter of the head is 3/4 inch and the angle is 60 degrees. What is the best way to do this? I was thinking a 3/4 inch 60 degree center reaming counterbore, am I on the right track? Thanks.

By the way, I am new to metal working, so hope that I have the terminology correct.