.224 Boz
Introduction The '''.224 Boz''' cartridge was developed in the late 1990s, designed as a candidate replacement cartridge for adoption as the standardized NATO ("STANAG") Personal defense weapon PDW round, originally solicited to replace the longstanding NATO standard (STANAG) 9×19mm Parabellum. It was going to be the British entry, to be evaluated alongside the Belgian FN 5.7x28mm and the German HK 4.6×30mm armor-piercing cartridges. The solicitation would also seek to find, test and standardize a PDW cartridge capable of, at the minimum, defeating the Collaborative Research Into Small Arms Technology (CRISAT) body armour of the time.
Design The .224 Boz began as a 10mm Auto case necked down to . Original trials were successful, with this round firing a  projectile chronographed at over . During development a version based upon the 9x19 Parabellum case was also evaluated, which carried the significant advantage of being able to be utilized in pre-existing NATO standard 9x19 Parabellum caliber firearms by means of a relatively cheap barrel and caliber swap. The 22 TCM takes advantage of this same concept in its sub-variant, the 22 TCM 9R.
See also *.22 TCM*.22 Spitfire*HK 4.6×30mm*5.7×28mm*Table of handgun and rifle cartridges
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