What is the origin of the idiom "get the lead out" and when to use it?

The origin of the idiom "get the lead out" can be traced back to the world of military drill and discipline. In military contexts, the command "get the lead out" was used to instruct soldiers to remove the lead plug from their musket barrels before firing. The lead plug was inserted to protect the barrel during transportation and storage, but it needed to be removed before engaging in combat. It can be used in various situations where a sense of urgency or impatience is felt, such as when time is running out, deadlines are approaching, or efficiency is necessary.