I have been shooting 308 185 gr Berger Juggernauts at 500 yard F-Class matches. But want to develop a load for 1000 yard matches with Berger 200.20X and 215 gr hybrids. I will be using Varget powder. Rifle is .308, 30 inch, 5 Grove, 1:10 twist. What range of powder loads would you recommend for each and what velocities are you seeing?