I'm running 243AI's and 25-06AI's. It still comes down to bullets. my '06AI runs 100NBT's at 3475 and the 243AI runs 105VLD's at 3200. I realize this isn't an apples to apples comparison but the 6mm's just have the BC advantage and theres no way around that. By the time they both reach the 300yd line the 6mm 105 has caught up to the 100NBT and from there on out the 105 beats the 100NBT in wind drift,drop, and retained speed/energy. Now don't get me wrong I love my 25-06AI but they just don't have the high BC bullets available that the 6's do. My 25-06AI has accounted for 5 head of game just this season, 2 antelope and 3 whitetail, at ranges from 80-460yds and its worked great. but anybody who says its some great step up from my 243AI is doing nothing more than kidding themselves.....or they've never ran them both side by side.