This was a poor choice of words, considering what it was referring to. Yes, guns do smoke after being fired. And, as Faldage said, the meaning has been extended. As in, if you come into a room and find one person shot and another holding a smoking gun, you can assume that there is a very high likelihood that the person holding the gun was the shooter. After all, the smoke has not dissipated, so the gun has been fired within the preceding few seconds. It is unlikely that a third person would have been able to make a complete escape and be undetected in that amount of time.

If I may, however, I'd like to post a reminder that in the past, political opinions and comments on this board have led to some ugliness; and I hope that we can avoid that happening again. Thanks, everybody.