I'd like to add a tip on checking for barrel bulges. Run your fingers down the outside of the barrel to feel for any bulges.
Also check for bent ejector rods by spinning the cylinder with it out and it should ship without wobbling.
Check the firing pin mount for any burrs or if it's loose.
Check the crane/cylinder closed frame fit on the front of the gun. Should be nice and tight without gaps or frame might be stretched/too much one handed opening/closing.
The cylinder shouldn't drag open when you release it.
The crown of the muzzle shouldn't be stratched.
Check cylinder stops for excess wear/abuse.
What was the S&W sing test used to check? When you pull the hammer back slightly and spin the cylinder and you can hear the clicking?