are bullet shapes critical, ie round nose vs flat vs hollow point?
Please assume that every different bullet is exactly that: Different.
Because they really are.
Best advice I can give is when starting with a new bullet, find as much data as you can for something similar, and start at the averaged 'Start' load.
Bullets vary in material, construction, bearing surface, malleability, length, weight, and friction coefficient. Even, sometimes, by lot....