I once read a story about a gun that was either demonic or perhaps a shapeshifting alien. It was sentient and kind of took over the mind of people who came into contact with it, then it used those people to sow evil, causing assassinations, starting wars, etc. Possibly the thing took other forms before guns, and drifted from person to person through the years (spears, swords, etc). I believe it was a short story in a horror or science fiction anthology or magazine. I think it would have been published sometime between the 70's and the early 90's, I think the story referenced the JFK assassination. I know this isn't much to go on, but can anyone think of it? I could swear it had a title like... 'The Automatic Gunman" or somesuch, but maybe I'm just crazy. Thanks for any guidance!