Re: C.O.L. A.O.L. B.T.O. ??
Ive only got a second... so hopefully others will fill in the gaps.
COL is the length from meplat(bullet tip) to head of case.
AOL is the length from case mouth, to head, or alternately an evil empire responsible for the "dumbing down" of the internet... however, their free cds make excellent shotgun targets.
BTO is base to ogive... in this instance however, the base in question is on the bullet, not the cartridge.
headspace on most cartridges is measured from the datum point (or middle point) on the shoulder to the head. Theres a number of ways to measure it, but the most accessable is the stoney point gauge.
base diameter is the max diamerer in front of the extractor grove.
Shoulder diameter is the diameter at the junction of the shoulder, and case body.
Freebore, throat, leade.... all area in front of the case mouth, and while not interchangeable... are all talking, mostly about the same area. The # you are looking for, is the bullet Jam length... or the measurement from the head to the ogive at which the ogive of the bullet makes light contact with the lands.
Freebore would be the distance you seated your bullets back (deeper into the case) from this #
The leade is the angle area at the very origin of the lands.
Get the stoney point headspace gauge, and ogive inserts for the calibers youre loading for, and you will be good to go.