I believe the max is around 300-320 - not entirely sure though.
Max is 320 for me. I have never hit higher than that. I don't reang etoo much though.
Sounds like bs.
I've cannoned several thousand frost kills and I have observed, as Rs wiki states, that the max is indeed 300.
Are you using rigour/extreme ranges/void? I'm not sure if they affect it or not.

