I shoot 100 grain TSX and TTSX bullets out of a 257 Weatherby. The load I use is 72 grains of Reloder 22. I get velocities right at 3600 ft/second. I have a friend that says he uses 75 grains of Reloder 25 with the same bullets, and gets a little over 3700 ft/second. The Alliant website does show 100 grain loads with both powders. Does it sound prudent to try R25 with 75 grains?