I have been handloading for me 30-378 with Retumbo powder. I would like to use this powder for developing a good load for my brothers 300 Weatherby Mag. We are loading 180gr Accubond, weatherby brass, Fed 215 primers. I was thinking of starting off with about 80gr and checking the speed with my Chronograph. Any ideas or experiance with retumbo and a 180gr Accubond in the 300 Wb mag.?