I had a very positive experience with Mark in S&W CS today and wanted to share it. I've been using my M&P 15-22 in steel challenges and shooting just for fun for two years, now. I know I have more than 10K rounds through it.
Saturday I started getting light strikes -- one about every 10 or 15 rounds. This was strange behavior for a reliable rifle, so I stripped it down for a thorough going over. There was a chip out of the tip of the firing pin.
Frankly, a dreaded calling S&W CS out of fear they'd only help if I returned the rifle -- something I did not want to do. Turns out I had nothing to fear. I told Mark what had happened and that I needed a new firing pin. He said he'd have one out in the mail immediately.
This is the kind of service I've come to [almost] take for granted from Ruger, CZ-USA, and Hi-Point. I'm now delighted to know S&W will treat me the same way.
BTW, I have nine S&W firearms. This is the first time I've ever needed to contact CS. I'm 75, which should tell how reliable these other guns (revolvers) have been.
Update: Today (3-17-2018) I received the replacement firing pin (and spring) from S&W CS. That's fast.
With the proper tools (roll pin punch and roll pin starter) removing the old firing pin and replacing it is a five-minute job. I stretched the time a bit by thoroughly cleaning the inside of the bolt.