I get a little over 2700 fps using a max load of RL-22 (47gr)and a 140gr bullet out of a 29" barreled swedish mauser, you can load another full grain of the same powder in a stronger action, but the velocity gain isn't much. A 6.5x284 from all accounts pushes the 140 gr bullets around 3000 fps.
I am going by my Nosler manual and comparing a 140 grain bullet and there was 100 fps. 2900vs 3000 ..... I have to look this manual over again when I get home.
Ok I looked at Nosler number 5 at home and the max speed for the 6.5x55 with a 140 was 2785 vs 2925 for the 6.5-284