Idioms and Phrases with both barrels, with
both barrels, with
With full force, as in When I scolded her for stealing, I let her have it with both barrels. This term alludes to firing with both barrels of a double-barreled shotgun. [Colloquial; mid-1900s]
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.