I was today years old when I found out that the phrase "lock, stock and barrel" makes perfect sense. I already knew that the stock is the wooden part of a gun. What I didn't know is that in the days of matchlock and flintlock guns, the "lock" is the part of the gun with the hammer, ignition system and priming charge. If you took apart your flintlock (or matchlock) musket (or pistol) there would be three parts: The lock, the stock and the barrel.
In my head it now joins the list of phrases that come from ancient firearms technology like "keep your powder dry", "go off half cocked" and "flash in the pan".
I'm ashamed to admit that I had made up a kind of rationalisation in my mind for the phrase. I thought it was probably something to do with everything you owned in a warehouse: The (pad) lock off the front door, the stock you kept in the warehouse, and the empty barrel(s) you used to store liquids. Wrong!
The phrase wouldn't have the same poetry if it was coined in the day of self-loading rifles: "I emptied my garage fire control group, magazine, bolt carrier assembly, receiver, stock and barrel.
Richard "eggcorn" B