This thread has some decent info on checking a revolver before you buy it:
but omits a number of problems with new SWs:
1) Check headspace (gap between the cylinder and breech face) all the way around, not just at the top.
2) Check side plate fit, problem is they won't let you remove it to check it.
3) Check CAREFULLY barrel fit to frame if it's aligned correctly or crooked (rotated offline).
4) Look closely at the hammer and see if it has drag marks on the side, most are not centered in the frame.