.22 caliber .22 caliber /ˌdɒt ˈtwɛntiˈtuː ˈkælɪbər/

adjective

1. [American] Of or relating to the bore of a gun (or its ammunition) that measures twenty-two hundredths of an inch in diameter  ( .22 caliber [American] , .22 calibre [Canadian, British] , .22-caliber , .22-calibre )
   of or relating to the bore of a gun (or its ammunition) that measures twenty-two hundredths of an inch in diameter
    A .22 caliber pistol
   a .22 caliber pistol