From Wikipedia, the free encyclopedia. Colt 45 is a brand of lager or malt liquor in the US, introduced by National Brewing Company in the spring of 1963. Through a series of mergers and acquisitions, the National Brewing Company and its brands (including Colt 45) are today owned by the Pabst Brewing Company.ttp://www.nytimes.com/1984/12/07/business/g-heilemann-to-acquire-pabst-for-69.3-million.html. Colt 45 is available today in a multitude of packages and sizes. Cans are available in 12, 16 and 24 ounce packages and bottles are available in 7, 12, 16, 18, 22, 32, and 40 ounce packages.