My understanding is that parallel is the shank.
All reamers have 'lead in', I believe machine reamers have less than hand reamers though.
If you want a flat bottomed hole I suspect boring it is the best way. Making up a cutter would be fairly easy too, might be worth considering.
What works for me, is to drill a size down as close as possible (0.1mm metric or 1/64th imp) and then machine ream it fairly slowly (say 30rpm) with a bit of lube brushed in and a decent feed rate. Too much RPM and I find I end up with hexagonal holes!