John,
You are absolutly right as long as the bullets are the same. Now lets talk overall COL, and lenght of throats. That is where there is a differance. A 6.5X55 Swede will allow a longer COL and most (never seen one that did not) will have a longer throat than a 260 Remington. Bottom line the bullet in a 260 will have to eat into the area that could be full of powder. Below 140g I have not seen a differance. 140g and above the Swede will win ever time.

Funny post for me.. Coming back at someone I respect and admire.