What does the 45 in dixie 45 mean?

This is one version told in New Orleans, the home of Dixie Beer: In a bar across the street from Dixie Brewery the owner kept a .45 revolver handy in case there was ever any trouble. The brewery workers hung out at the bar after work or on breaks and were in the habit of calling the owner ".45" in reference to his weapon. They would shout, "Bring us another round of Dixie, 45!" After a time they suggested to the brewery owner that the brew should be renamed "Dixie 45" and he agreed.