Safety testing exceeded the ANSI/SAAMI requirements adopted in May 1990. These included dropping a USP with a primed cartridge and decocked hammer on a variety of hard surfaces without discharging. The USP surpassed these commercial requirements, as well as German Army and police tests, including repeated drop tests from six feet (1.8 m), hammer first, onto a steel backed concrete slab. Proof round firing resulted in no cracks, deformations, or increase in head space. Attempts to fire the USP pistol with an unlocked breech proved unsuccessful.