If its a V2 box and you use it in winter with a pretty stiff spring, there's a good chance the front of the shell will go first. Or even if you're using a really stiff spring, any season. That's why they sell reinforced ones.
Not a breakage per se but sometimes the trigger switch contacts get oil/grease on them and/or a high power battery is used that causes a lot of arcing. Eventually the contacts get gunked up and stop being conductive and need to be cleaned (sanded).