Before I'd use 120gr bullet's in a 6.5, I'd use 120gr in a 25-06! The standard 6.5's have little if any advantage with their light bullet's over a 25-06. On the other hand, nobody I know of makes either a 130gr or 140gr bullet for the 257 cal! Difference between the 120gr 6.5 and 130+gr 6.5 is velocity. The higher velocity could make the light bullet fail. If you simply want to get to 3000fps, my 25-06 shoot's 117gr Hornady's at 3079fps measured! Stepping up in cal so you can drive a light bullet faster doesn't register with me. My favorite bullet in my 6.5x06 and my 6.5x55 is the 140gr bullet but I do have fit's about the 129gr bullet now and then.
