An idiom meaning to hit the mark every time; unfailing or infallible. Often used figuratively to mean always succeeding or being right.
彼の予想はいつも百発百中だ。
His predictions are always spot on.
射撃の練習で百発百中を目指している。
I'm aiming to hit the bull's-eye every time in shooting practice.
そのマーケティング戦略は百発百中というわけではないが、効果が高い。
That marketing strategy isn't infallible, but it's highly effective.
冗談で『百発百中の秘訣は何？』と聞いてみた。
I jokingly asked, 'What's the secret to being right every time?'