Just built 300 WSM 1000 yard gun, had one day after break in to work loads before match. Tried something that worked well. Knew components H4350 powder and 190 JLK bullet, F210 primer to try. Only issue as load. Load range was 58-61 grains. Loaded cases (one each) in .3gr increments. Zeroed at 410 yards at bottom of large target with lowest charge. Shot and chrono'd one round at a time starting with lowest. Marked on paper at bench exact bullet location. About 3 shots into it, 4 bullets clustered, then 3-4 shots later 6 bullets (each different charge) went into 1 1/2inches. These clusters are supposed to be "sweet spots" for your barrel and load. Due to short time and not able to do further testing, just split the diff between top and bottom of top cluster. That gave me about 2900 FPS with load not near top on pressure but accurate. At match next day shot 3 sub 8" ten shot groups at 1000. Further testing will work on seating depth and fine tuning. But great way to find sweet spot to start with. 15 rds versus 15-5 shot groups.