For bullets like the Hornady V-Max:
I will measure OAL like you are doing.
But with lead tipped bullets like the Hornady Spire Point:
I utilize the Hornady Lock-N-Load Bullet
(formerly Stoney Point) Comparator (using the ogive as "charles p" mentioned) for a more precise measurement, as the soft lead points tend to be flattened and lengths can vary greatly.
Bill