The .260 isn’t old, or new for that matter. And I don’t believe the 6.5 caliber is any more aerodynamic than any other caliber. Having said that I think some of the milder 6.5’s are in a real sweet spot for the average medium game hunter and can do adequate triple duty on large game and varmints if needed. So far I’ve only used my .260ai on deer, hogs and a speed goat. Hoping to pull a elk/mule deer double with it one of these days!