I have returned four revolvers to S&W over the years. It takes a little bit of negotiation on the phone with the service rep to get them to give you a shipping label. It depends on the model and when it was manufactured, and what kind of problem needs to be solved. The return time ranged from 4-6 weeks. These are the individual circumstances and what transpired (1) a 29-4 that was shot loose and had endshake. S&W said "send it in" but I had to ask for a shipping label, which was provided. Revolver was restored to factory specification perfectly at no charge. (2) a 27-2 that had the rear cylinder lock pin broken off and cylinder endshake. Also had to ask for the shipping label. Had the frame sideplate re-blued as well. Revolver was returned in perfect working order, bluing blended well with the rest of the finish. Charges were about $85. (3) 625-3 that had a loose cylinder yoke, which could be pulled out of the frame a little bit even with the retaining screw tightened down. Shipping label was provided and revolver fixed at no charge. (4) 625-3 that had side-to-side play in the cylinder that allowed the cylinder to slip past the frame stop on occasion. Had to ask for a shipping label. A new yoke needed to be fitted and I had a MIM trigger replaced with a steel one. I also asked for the springs to be replaced with factory springs. Revolver was returned in perfect working order, charges were about $130.
All in all, I was satisfied with these experiences, and happy with the knowledge that the repairs restored the revolvers to factory specifications. I was not charged for return shipping if the repairs were done at no charge, but when the repairs were charged, return shipping was added.