So I bought some super performance powder to for my 257 ack and my 300 WSM Results with my RBCS chrony were as follows All Rounds were loaded with 115 VDL COL 2.85 out of my ruger m77 long action with 28 inch barrel. 48 gr. 2900 fps 5 shot average. Group 1.25 inches. 100 yds 51 gr. 3134 fps 5 shot average. Group. 0.75 inches 100 yds At 51 gr I still had no pressure signs I normally shoot RL 19 at 48 gr at 3050 fps As for the 300 WSM out of my tikka T3 lite Shooting 178 gr Amax. 70 gr 3010 fps 1.0 groups at 100 I also tried a few at 68 grains they were 2973 fps I think I will stick with my RL 17 for that gun. 68 gr pushes that Amax at 3144 with no pressure signs and 0.5 inch groups at 100yds and 7 inches at 700 yds An interesting note I also had a friends Christensen arms on a rem 700 in a 300 WSM Shooting the RL 17 and the super performance I had very flat primers and deep craters on my primers. Over all I still would like to try it in my 223 WSSM and my 223 I will let you know of the results.