I really like Redding's "Instant Indicator". It is a die that will measure BTO, OAL, case length, or headspace, and does it with remarkable repeatability. It doesn't require the developed "touch" needed when using a caliper
Are you shooting for aggregate groups in competion or shooting against a buddy for beer money. The level of what matters is directly in proportion to the goal. If you aren't familiar with bullet pointing, and you dont consider weight sorting primers then you may be deeper down the rabbit hole than you need be.I shoot at only 100yds. How many thousands off of each cartridge does it take to make a difference in group size? What I mean is if I have a variation of .002 or.003 in ogive to base will that show up in the size of my groups?