As a pointer for future experimenters, for metal something that works well:
Take a newbuck mitt (i.e. a leather glove or mitten with the rough side out) and put a bunch of talc into the palm. Now handle the gun with the glove vigorously for a TV show duration. If you do it right, the talc will abrade the bluing off the edges, high points and corners. It ends up looking naturally worn.
For wood, strip off any applied finish and set the stock outside with a coffee spilled all over it. If you wipe on a streak of motor oil here and there, all the better. Wait until the stock gets rained on and then let it dry in the sun. Take it inside and coat it right away with raw linseed oil. It will look issued.