in full swing
Also, in full cry. In full operation, at the highest level of activity. For example, After the strike it would be some time before production was in full swing, or His supporters were out in full cry. The first expression, dating from the mid-1800s, alludes to the vigorous movement of a swinging body. The second employs full cry in the sense of "vigorous pursuit," a usage dating from the late 1500s that may be dying out.
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