Many posts about bullet "jump" to the lands mention changing COAL OR OAL to increase or decrease this "jump" a precise number of thousandths of an inch. I am of the impression that COAL AND OAL refer to the overall length of the cartridge from base of the brass to the tip of the bullet. Because all bullets, even the best in the same batch, have slightly different (.001" to .005") ogive lengths, how can one accurately judge the precise length of "jump" just by seating the bullet deeper or shallower into the case. Seating the bullet deeper will certainly increase this "jump" and seating the bullet shallower will certainly decrease this "jump". However, the overall length of the cartridge does not determine the "jump" to the lands. The length of the cartridge from the base to the ogive of the bullet is what determines the amount of "jump". One needs a special procedure and gauge to measure this distance.

Please feel free to correct any misunderstanding I have about the calculation of bullet "jump" and the abbreviations describing the length of the cartridge from the base of the case to the ogive of the seated bullet.

How is this measurement-base to ogive length-described in reloding terms- OAL to ogive, OALTO, etc. ?

Thanks in advance.