I recently bought a 4" 617, put some Herrets I had on it and am very happy with it. Also have a 6" I've had 2-3 years which I wanted to scope. That has worked out well also. Probably I don't know what to look for as to all these problems but they get shot a lot, are accurate and work perfectly. Triggers are nice. If something goes awry I'll call S&W and it will surely get fixed.
Bo