I can only get about 2650-2700 out of my 308(22" tube) with a 165gr partition and RL15(IIRC, 45.0 grains)
I suppose I could push it a little harder than that, but I still don't think I could get much beyond 2700fps(safely.)

"For joy of knowing what may not be known we take the golden road to Samarkand."
James Elroy Flecker