The Dictionary of American Slang, Fourth Edition by Barbara Ann Kipfer, PhD. and Robert L. Chapman, Ph.D. Copyright (C) 2007 by HarperCollins Publishers. Cite This Source
Idioms and Phrases with great guns
Very energetically or successfully. This colloquial expression usually occurs in the phrase
go great guns, as in They're going great guns with those drawings. The expression comes from British naval slang of the late 1700s, when blowing great guns meant a violent gale. Harry Truman used the term in Dear Bess (1945): “We have been going great guns in the last day or two.”
great gun. Also
big gun. An important person, as in All the great guns came to the reception. This usage is heard less often today.
[ ; early 1800s