Smith and Wesson has done a very good job with all of the revolvers and 3rd Gen autos I've sent them for service.
One thing I make sure of before sending them in is that they are SCRUPULOUSLY cleaned. I tend to think that guns are not too unlike cars. Meaning, a mechanic (or gunsmith) is more inclined to go the extra mile if he/she has a clean canvas from which to work.
I volunteer at my LGS in cleaning guns taken in for service, or ones that have been taken in on trade. I spend extra attention on S&W revolvers, 3rd Gens, 1911s and Beretta 92-series guns. Why? Because I know them. Many would shudder at the sights I see when folks bring in guns for service, wondering why they cease to function.
Many times it's a lack of cleanliness or lubrication. I help them out by giving them a quick clean and lube. When I come out to meet with them 10-15 minutes later, they're dumbfounded. I gently remind them that a firearm is a mechanical device and is subject to the laws governing mechanical contraptions: Dirt, grit and lack of lubrication will kill ANY mechanical device.
Whenever any of my firearms go out for service, they are so clean that you could eat off of them. It must be a Marine thing. The first thing I do when I get a firearm home, is to tear it down and clean it.
Another quick aside. About 3 weeks ago, I was given the high honor of tearing down and cleaning a 1934-vintage .38-44 Outdoorsman with a 6-1/2 barrel. The gun had never been apart in its 81 years. The years were kind to her, as she had all of her rust bluing and was still very tight. 3-1/2 hours' cleaning netted a beautiful example of S&W glory. I can't imagine the artisans who made her and the tools that they used to build her. Her insides were not molested (or all that dirty...) in any way. She was given a gentle cleaning and sent on her way.
Last week, her new owner and I discussed her and the subsequent range trip. He was indeed grateful for the preservation that I gave her. THAT makes all of my work worthwhile. I feel good when others like the work I've done for them on their firearms.