If you obtain a comparitor, you will see that your O.A.L. will be very close to each other because you are measuring from the bullet's ogive, and your die seats the bullet using the ogive and not the bullet's tip. Every bullet's length is not the same from tip to base, so you are going to obtain different O.A.L. measurements when measuring from the bullet's tip to the bottom of case. The measurement from the tip of the bullet to bottom of the case is important when it comes to the cartridge fitting in the magazine. The measurement from the bullet's ogive to the bottom of the case is very important because it lets you know how long the cartridge is, and if it is long enough to reach the riffling or not. According to "Nosler Reloading Guide Four" "Optimum accuracy is usually achieved with a slightly longer cartridge length." In some instances the cartridge's O.A.L. will be to long to fit in the magazine because the length the cartridge needs to reach the riffling, exceeds the magazine's length. I suggest you purchase a Stoney Point O.A.L. Gauge (Stoney Point Modified case also needed), and a Stoney Point Bullet Comparator. Good luck.