What size drill for 2.5mm reamer?

[Gazza]

Well, the 410 renovation has gone from a quick re-blue and stock oil to a total strip down and repair seeing as the sear pin hole and pin are worn out which is affecting the reliability of the safety catch.
After looking at it for ages and measuring many times it seems I will have to go out to 2.5 mm final diameter soooooo......
What size drill will I need so as to run a 2.5mm reamer through? Can I use a 2mm drill or is 0.5mm too much to ream out?
I'm guessing it will have to be an imperial size due to 0.5mm being too much?

[ovenpaa]

You could try 2,35mm - 2,4mm however you must drill the hole with care. I only use Guhring cobalt drills and often find the finish is such that reaming is not necessary.

[Gazza]

Thanks Mr Paa
Time to do some ordering of bits :)