I bought my first M29 in 1980. I was 20 at the time and every round that went through it was a 240 SWC over 22 grains of 2400. After many of these rounds the end of the center pin mushroomed and it was hard to open the cylinder. Contacted the factory shipped it back and they totally rebuilt the gun and shipped it back at no charge. After many more of these rounds it went out of time, back to the factory, another overhaul free of charge. After more rounds, the trigger stud broke, back to the factory, repaired, rebuilt, and reblued at no charge to me.
I really can't blame the gun, it suffered through a lot of abuse, I believe that the loading manuals now have a lesser charge of 2400 as the maximum. I still have the gun but it is fed light to mid range loads exclusively, it has been through enough and earned semi retirement.
In short my experiences with Smith's customer service has been exemplary and I have no complaints. I have shipped a couple other guns that had issues new out of the box and every time things were handled quickly and done right.