Belted Magnum
Also: Belt
A cartridge case with a raised belt just ahead of the extractor groove that sets headspace, a defining trait of many classic magnum rounds.
A belted magnum carries a raised band of brass, the belt, encircling the case just forward of the extractor groove near the case head. That belt is what stops forward travel in the chamber, so it controls headspace much as a rim does on a rimmed cartridge. The design traces back to early British nitro-express rounds and became the signature of the Holland and Holland family that spawned most popular belted magnum cases.
In practice the belt is a holdover that modern shoulder-headspacing designs do not need, and it can complicate precision handloading because the case still stretches just ahead of the belt. Many reloaders end up sizing belted brass to headspace off the shoulder anyway, and newer high-capacity magnums have largely abandoned the belt in favor of a sharp shoulder.