The Keith Floyd approach to reloading is to be avoided at all costs. That's why the figures in the loading data tables are exact - to ensure that reloader correctly replicates them.
Trying to best-guess the laboratory can only end in much pain and expense - maybe even injury and death to the shooter or those nearby.
Your doctor pal really needs to be TOLD that his reloads are not welcome on the club range - that might give him some pause for thought. Getting denied use of the range will inevitably cost him his FAC.
tac