Lock Stock and two Smoking Barrels

Here comes the origin of the word Lock STock and two smoking barrels...

I've been wondering about this one for a while.
The lock was the firing mechanism of early types of firearms, such as the firelock, flintlock, and matchlock. It’s likely the name was given to the mechanism because it looked a bit like the primitive door locks of the period. The stock is the wooden handle of such a firearm. The complete weapon consisted just of the three parts of lock, stock and barrel, so the expression means “everything, the whole thing”.

Perhaps oddly, it came into use only in the early nineteenth century, when such weapons had been in use for nearly three hundred years (the flintlock musket had been introduced early in the seventeenth century). Perhaps it was a result of standardised industrial processes that had by then only recently been perfected. This might have crystallised the idea of a musket as a set of interchangeable parts rather than a device all of a piece. It was also true that the American War of Independence and the Napoleonic Wars saw more flintlock muskets in use (the Brown Bess, for example) than at any time before or since.

The first reference in the Oxford English Dictionary is to a letter of Sir Walter Scott’s of 1817: “She wants stock, lock, and barrel, to put her into repair”. It may in fact have been invented by him.