Your gun may dictate max cartridge length you should use for a given bullet. Most magazines will accept FMJ's at max design length (SAMMI Spec). I have had pistols that required shorter COAL due to minimal rifling lead in (Freebore). Bullet shape combined with overall length may effect how well they ramp into the chamber.
When using a new bullet type/brand or gun I start by loading a dummy cartridge long by .1". I then insert it in the chamber of my barrel and determine how much too long it is. Once the freebore is determined I set bullet depth to leave .02" between bullet and rifling or to dimension listed in load data being used. If too long bullet to rifling contact may prevent going into battery reliably.
I find that testing samples over a range of charges will lead you to better accuracy.