Im just curious to know how long magazines last. I have the original mags for my usp 45c and glock 23 that are both 8+ years old. They both still feed flawlessly and lock the slide back when empty. I use to shoot a whole lot more years ago so literally thousands of rounds have been though these mags. These are currently my oldest firearms so I was wondering what's the oldest mags you have that are stock and still work. What is the recommended time frame for mag replacement?