I figured out a long time ago that buying new Glocks was pretty damned stupid. I've never been able to differentiate my Glocks that I bought used from my Glocks that I bought new. Glock will fix your Glock free, forever, whether you're the first or fiftieth owner.
"Why would anybody trade in a reliable Glock (or any other reliable firearm)?" That question doesn't deserve an adult answer!
"Why would anybody trade in a reliable Glock (or any other reliable firearm)?" That question doesn't deserve an adult answer!