Apparently right after a Dirty Harry film came out, a bunch of people would buy .44 Magnum revolvers. There was little interest in them before, they didn't even make them continuously, but after the first film they doubled the price and they couldn't make them fast enough to keep up with demand. A couple of months after each film, there was a surge in second hand versions on the market, because people found out that the most powerful handgun was powerful.
(Assuming that it actually was the most powerful handgun, that's another issue)