300 Dakota, talk about limited load data. I have tried H4831, RL22, 7828ssc, and Magnum. 4831 shot well with 185 Berger, and I settled on 7828 with 200 Accubond and 215 Berger.
3250 with the 185. Retumbo may work with 180, might be too slow. Friends have told me Retumbo is a little high strung...I'm trying H1000 next. Good luck!