I have a newly installed (75 rounds) 26" Bartlein 5r 9.0 twist barrel chambered in .243 AI. I have been working up to now 45.0 gr. of WIN 760 and a fed 215 primer. Using a jump of .010 I am getting the following (same load for both bullets): 87gr VMAX - avg vel - 3430 fps 75gr VMAX - avg vel - 3574 fps I still have room in the case to up the powder, I am getting no sticky bolt and the primers are not smeared. I am not sure I see any point in going any higher in the velocity with these bullets, but, feel I have not reached the top. What are you veteran 243 AI shooters getting with the 75 and 87 gr VMAX's. What is a reasonable "shooting" velocity for these in an AI.