Overloaded reloads? Failure to lubricate? Using lead ammo in stock barrel? The Glock like anything man made is prone to breakage. Have spare parts on hand in your range bag, and I mean a spare part for every component in your Glock, with you at all times at the range is important ( along with CLP ). Every spring, pin etc. ( If you have the money, then extra barrels ) If something does fail, you can replace it right away. That is the wonderful thing about Glock. It does not require much to fix. Happy shooting!