Honestly, the 8 second cool down per shot seems a bit unnecessary. I think a better way to achieve what you guys are going for (preventing people from camping in the back of the map) would be to just make it so that Ice Breaker regenerates an entire clip 30 seconds after the clip is emptied.
-
After the gjallarhorn nerf icebreaker would likely be the way to kill bosses of camping in the back of the map the whole time. So they don't want people doing that, instead of making it easier to camp in the back of the map they are discouraging you from doing it.