Some like BB bullets because they start into a case easier than a flat base bullet.
Some say the flat base bullet help prevent gas blow by and a
few more things.

I don't have trouble seating flat base bullets and in pistols I
don't worry about any stinking gas blow by. Over the years
I have had accuracy with BB and FB bullets in lead or jacket coatings.

I even have a Lead FB, RN lead bullet that is accurate out of a
snub nose J frame !!

I guess I am not too fussy.