The loading data for the 6.5x55 is usually pretty low because most rifles in this caliber are Military surplus rifles. The Swedish Mauser which are the bulk of these rifles is not as strong as the 98 mausers and some of the others. However in a factory built rifle there would be no reason that the velocity of both with 140 grain bullets would differ much.

That said, the 6.5x55 does not lack excellent performance on all big game at the velocities obtained buy the older Mausers. I load the 140 grain to about 2700 fps. Most factory ammo in this weight won't beat 2600. Even at that its a great game taker. One of the calibers that totally defies its on paper ballistics.