I have had my 4506 since NIB over twenty-years ago. In all that time, it has devoured everything (even my shoddy hand-loads) with no memorable history of problems. It's cycled literally tens of thousands of rounds, and I have NEVER replaced a single thing. Not even the recoil spring has tired. Just amazing.

The ONLY complaint I have with my pistol is that there is a glaring manufacturing defect with the front of the slide. In the recessed front, ahead of the dust cover (not sure the proper term, to be honest) one side has noticeably deeper machining marks then the other side. I'll have to post a picture when I get the chance. It has no affect on performance, but someone at S&W quality should be ashamed of themselves for their lack of attention back in the day...