I've been looking at 586's lately and notice that many of them have the "M" stamp indicating they were returned to the factory for service. Many of them for sale on variuos auction sights specifically state no "M" stamp. I am wondering if there were warranty or other issues with the model 586? I never see anything about the "M" stamp when shopping for other model S&W revolvers. Any info about this would be appreciated. Thanks, Dusty