One of the results of mixing imperial and metric designs is that you always miss out on the appropriate tools. Off-size drills are the favourite lacking tools. As I mentioned on another forum I started my career in the great Machine Shop of Philips (that now under another name produces the positioning hardware in the ASML chip making machines). An old hand in the shop once showed me how to grind a drill for an off-size. In principle it is quite simple. Say you need to drill dia 7,8 mm. You take the next smaller drill size available, say dia 7,5 mm. Difference is 0,3 mm. Now you grind the point of the drill half the difference i.e. 0,15 mm excentric. It takes building up some experience, but it works well. As long as you start drilling from a good starting indentation, so no centerdrill but a short stiff 120 degree top angle starting drill. For a blind hole this works ok, with a thru hole you put a sacrificial piece of material underneath.
This is why I have taught my children to practice safe computing. 
