[beta678]

Hm... after the hop up chamber it might be nozzle wing/arms.

Apparently they can break, though I've never been able to manage it. The newest nozzles have reinforced arms/wings so I wouldn't worry about it if you get one of those. If not, they're relatively cheap to replace.

Continuing after that, I guess it might be some of the trigger group components like the hammer, sear, etc. I've only heard of them breaking, never managed it myself but I doubt its common enough to worry about. There's steel replacement parts for them if it ever happens anyways and they're relatively cheap as well.

Wouldn't worry about any of those areas though, while they're the most common areas to look into after the hop up chamber, those issues aren't common enough to worry about.