Longman Dictionary of Contemporary English
business end
noun
EXAMPLES FROM CORPUS
▪ But it was at the business end where the main difference lay.
▪ Her hair, left to its own devices to dry, looked like the business end of a witch's broom.
Wiktionary
business end
n. (context idiomatic English) The part of a tool or other similar item, that is physically used for its operation, rather than the part which is held.