Cartridge overall length
The length of the complete loaded round, base to bullet tip.
Also called COAL, L6
C.I.P.’s L6, and the figure that decides whether a cartridge fits a magazine. A round longer than the magazine well cannot be fed from it however well it fits the chamber, which is a real constraint on how heavy a bullet a given rifle can use.
It is a maximum rather than a specification. An ammunition maker seats the bullet where it likes within that limit, and the same cartridge loaded with two different bullets will have two different overall lengths.