Limited by the time it takes to regenerate ammo. If you're fine with taking one shot every 4 seconds then Ice Breaker is for you. Don't get me wrong; Ice Breaker is ideal for sitting on a rock somewhere, taking your time and killing an unlimited amount of enemies, but for pure damage output and general efficiency, there are far better options. I have nothing against Ice Breaker. I have one and it's good at what it does, but so long as I have ammo and I'm not in need of solar damage; I'll use Praedyth's Revenge instead.