Mine is still as secure as when I bought it. It's only been about a year at this point though. It's an all metal latching system though that uses a spring steel split lock esque washer. If that washer were to ever get warped it'd be easy to replace though as it gets removed when you unscrew the feed. The mechanism on the cap is just angled metal as well. It'd take a lot to wear it down I think.
Edit check out this video by Doodlebud https://youtube.com/watch?v=zTYYYx6i47c&feature=shareb
When nature says "fuck you in particular"