Thanks for posting your results/solution. I personally find huge value when the OP comes back to explain the actual issue, the resolution, and the results afterward.
As far as brakes go, I can personally speak to the APA brakes. I have a "fat bastard" on a 338LM and it works awesome. I think the "little bastard" is appropriate for 300WM. If nothing else, check out their promo video as it is highly entertaining:
I've heard great things about Holland and Painkiller brakes as well, but have never been behind them.