They had one that affected a limited serial number range, and no other issues. Fortunately the 50 or so I was responsible for were not effected. S&W got in front of it and fixed it. It required the replacement of a single pin, IIRC. Sig outright accused folks who had problems with the 320 of lying, including those who caught a bullet from one.
You either make a gun that works, or you dont. Sig has about a decade and a half of poor QC and beta testing on their end users under their belt. I was a VERY satisfied user of their products, until I wasn't, having exemplary CS until a certain someone took over the company. Perhaps they will restore their former glory at see some point, and I'll look at them again. Perhaps not. When my agency went to Sig from S&W twenty years ago I was very pleased, because the Smith of that period was every bit as bad (if not worse) than Sig today. The worm has turned, so to speak. I'm now running M&Ps with complete satisfaction. And if they go the way of today's Sig, they will be replaced with something else. I managed a fleet of about 600 of each, and had fewer problems with the M&P. I readily acknowledge that could end with a change in their corporate culture as well. I learned a long time ago to marry brand loyalty with function and service when it comes to choosing a firearm.