For pistol:
Make a dummy round ( no primer or powder) and seat bullet so oal is on the longer end for bullet profile
plunk test on all my barrels in that caliber
seat about 0.010 shorter than longest oal that passed all barrels
load dummy round in mag and check feed/extraction
check books for loads with my powder and bullet (or similar bullet) and make sure load data was not using a longer oal. Shorter ok.
I start around middle of load data and work up 0.2 to 0.3 gr depending on case size/charge weight
chrono loads / check accuracy / pressure signs
For rifle:
dummy round with cut slots in the brass neck to allow the dummy bullet to slide so the bolt is easier to close
for bolt guns that will take longer rounds, I seat 0.015 or 0.020 off lands (use hornady comparator)
for mag fed (AR's), I seat to max oal that will reliably feed in mags
check function with dummy round
middle of road load data and change powder wt in 0.5 gr increments. Fine tune the best goup if I'm bored by changing the charge in smaller increment and oal.
chrono / accuracy / pressure signs
Not saying this is the best way, but it's how I do
