In Episode 4 of Straight Talk, we cover the differences between Cartridge Overall Length (COAL) and Cartridge Base To Ogive (CBTO). For a detailed description on how I measure CBTO, check out these links: http://panhandleprecision.com/measure-bullet-seating-depth/ https://www.youtube.com/watch?v=NR3-7XDGiDc&index=2&list=PLX2aeFXzRrvcu1ZwFK4_MkiEsrLuX97n0