If it's a hand reamer then yes it's tapered for the first 15 to 20 mm. A hand reamer is one that has a square on the blunt end so that it can be turned (clockwise) with a tap wrench. 6.75 or 6.8mm should be fine for the drill. Use some oil on the reamer to help with the cutting.
Cheers
John
Thank you, much appreciated.
