The 5.7mm High-Velocity Auto descends from the old 5.7x28mm cartridge developed in the late 20th century specifically to defeat body armor at pistol distances. That mission statement hasn't changed in two hundred years — what's changed is the armor it needs to defeat. Modern soft armor integrates ceramic-fiber composites and reactive gel layers that stop most conventional pistol rounds reliably; the 5.7mm HV Auto's answer is a long, small-diameter projectile moving fast enough to defeat those layers through mechanical penetration rather than energy transfer. Current production uses a caseless-adjacent hybrid: a conventional brass case at the head with a combustible polymer body that reduces ejection complexity and increases feed reliability in compact platforms.

In GLMZ 2200, 5.7mm HV Auto has a complicated legal status that varies by borough. In corporate-administered districts, possession of the armor-defeating variant (marked AP-HV on the case head) requires a Tier 3 munitions permit that costs Φ800 annually and involves a background audit. In outer boroughs, nobody is checking. The round is popular with Arcturus Civil Security plainclothes units, mid-tier fixers who operate in environments with armored opposition, and the specific type of Excluded who has acquired an understanding of the local threat landscape through painful experience. Tessera Corponation's munitions subsidiary produces the dominant commercial load and aggressively litigates against gray-market reloads.