The original terminology was ‘Lock’ and ‘Load’ and originated with the military and the M1 Garand back before WWII. The Range Officer would issue a series of commands to the recruits on the firing line.

“Lock”, ordered the shooter to pull back the operating rod that cleared the chamber and locked it in the open position.

“Load”, ordered the shooter to insert the clip, push it into the magazine and let the bolt cycle forward chambering the first round.

The next command was, “Commence Firing”.

These commands have morphed into the popular jargon ‘Locked and Loaded’, which refers to a live round in battery ready to be fired.

This is for those who didn’t already know that.