I really haven't found a wealth of info on successful real world load data for this combo and I'm hoping I didn't waste my money on these. Ballistically, they are WAY flatter flying than the 300gr otm out to 1200 or less when compared to my current load of 300s under 90gr retumbo, flying at about 2700. From what little I read I should be able to get 3000fps pretty easy on the 250s out of my 29" barrel. Question is, what powder should I use and how many grains to start? I have retumbo, h1000, h4831sc, and h4350 on hand. I will consider other powder options but I prefer extreme powders for the desert environment I live in.