Ammunition Lot
Also: Lot Number
A single production run of ammunition or components; staying within one lot keeps velocity and accuracy consistent across a string.
An ammunition lot is the batch of rounds, or of components like powder, primers, and bullets, produced in one continuous manufacturing run under the same settings. Boxes are stamped with a lot number so the maker, and the shooter, can tie performance back to a specific run. Within a lot, the powder is from the same blend and the components are uniform, which is why velocity and point of impact tend to hold steady across rounds drawn from it.
Serious shooters buy match-ammunition in quantity from a single lot, because switching lots can shift average velocity enough to change the come-ups recorded in their dope. A new lot of factory ammunition deserves a fresh check over the chronograph and a confirmation at distance, since even small changes in the run can widen extreme spread or move zero. Handloaders apply the same discipline to powder lots, retesting a load whenever the jug changes.