Lock magazine into the magazine well and load a round into the chambre is what it had become by 1976 in the USMC. Speaking only from memory and experience. Appertained to both the Colt M16A1 and the Springfield 1911A1 both being detachable-magazine fed.
The range commands would have been --
- Ready on the firing line!
- All ready on the right!
- All ready on the left!
- With a magazine and 5 rounds, lock and load!
- Commence firing!
In the classes leading up to rifle range and/or pistol range day, the instructors explained it involved locking a magazine into place and loading a round into the chamber, and not doing so until commanded to do so.
Note that you can lock and load a .45ACP or an M-16A1 whether or not the bolt has been locked open or not. Thus by the 1970s lock and load had come to mean getting a cartridge into the chamber and ready for firing with a detachable-magazine fed weapon.
Buck460 is probably correct about the history. The M-1 does need to be locked-open before the clip can feed cartridges into the box-magazine well for loading. I have shot that rifle and I know how it works.
Not sure about a flintlock though. A blackpower shooter will need to tell us more about that issue.
We are probably going to need someone like F. Lee Ermy to settle this one for us. And even he is going to need to look it up, since Ermy is only from Nam daze, not from WW2 or earlier.
Russ, my friend, I take it you also never had to deal with --
- From now on you maggots will only speak when spoken to,
- And the first and last words out of your mouths will be Sir,
- Do you maggots understand that???