The result of these efforts is the ReX zero 1 semi-automatic 9 mm pistol series. ... The 3.85" single-piece barrel is cold hammer-forged from chrome-moly steel and Nitrocarburized like the slide.

Arex considered the variations in 9 mm primer hardness when preparing the Alpha for international distribution. European primers tend to need a more authoritative whack than American-made primers do.