I have had S&W revolvers for years, but now my model 66 cylinder locked. It appears that the ejector rod unscrewed itself enough to do it. I will have to get a gunsmith to look at it.
That's not a new problem; I don't think it applies to either older or new S&W but I remember a period (late 70's/early 80's?) when it was common, along with really rancid cylinder to forcing cone gap and alignment.