Go off half-cocked and go off at half-cock

To go off half-cocked means to act prematurely, to speak prematurely. To go off half-cocked is another idiom derived from the operation of firearms. To fire a flintlock gun, one must pull back the cock, or striker. When a gun is fully cocked, it is ready to fire. When a gun is half-cocked, it is not ready to fire. If one shoots with a half-cocked gun, the result will not be satisfactory. This fact translated into an idiom that describes someone speaking or acting in a manner that is premature, before weighing all factors or being fully prepared. Related phrases are goes off half-cocked, went off half-cocked, going off half-cocked. To go off half-cocked is the North American version of the idiom.

To go off at half-cock is the British version of the idiom, the definition remains the same.

Examples

That mattered to Mr. Biggs partly because he didn’t want the newspaper editor to go off half-cocked. (The News & Observer)

“One thing I’m not going to do is go off half-cocked like Mr. McCrum did,” he said. (The Texas Tribune)

Legislators so regularly float and often pass goofy bills — such as demands to sell state lands and open public waters to private fish farms — that they shouldn’t be shocked when folks go off half-cocked over a bill to eliminate age requirements for Wisconsin’s mentored hunting program. (The Oshkosh Northwestern)

“We don’t want to go off half-cocked and realize later that it should’ve been half its size or we could’ve doubled its size,” Hyden said.  (The Journal News)

Some of Langridge’s ideas go off at half-cock. (The Financial Times)

“Operation Forto” appeared to go off at half-cock, before the ringleaders had won the unequivocal backing of key generals. (The Asmarino Independent)