I might have the numbers in a file at home, but it's no big deal
to measure. I use gauge pins and measure across the OD of
a opposing pair ( assuming a even number of holes ) then
subtract the pin diameter. A couple of fired shell casings
would be close enough for loading block purposes.
Slip the drill or mill through a adjustable camphor cutter
set a depth stop and go at it.
I do em on a mill using the bolt circle function of the DRO.
Space the centerlines so whatever speedloaders I'm using
have about .040 to .050 clearance between their ods if
multiples are loaded at the same time.
Kinda like this
Dave