Yeah, I never heard that before, but I guess it makes sense. Would that origination also imply the same meaning, though, of a complete something-or-other? The lock, stock, and barrel of a gun are the entire gun. Does the lock, stock, and barrel of a store also imply the entire store?
This phrase actually refers to the parts of a musket: the lock was the firing mechanism, the stock the wooden part that supported the barrel and the lock, and the barrel, of course, is where the musket ball is loaded and fired from.