I have a Ruger M77 Compact in .260, and a Winchester M70 Classic Featherweight in 6.5x55, and I prefer the 6.5x55, but only because it has a long action, so I can seat bullets out and they will still feed out of the magazine. The .260 is in a short action, so heavier bullets have to meet magazine length restrictions and take up powder space in the case. In a single shot this will not be a problem, so it's probably a tossup. If you check reloading manuals they are almost identical in velocities. Either will work, but the Swede may have more freebore than the .260, which will necessitate seating the bullets out to be closer to the lands. My M70 had .390" of freebore, and it drove me nuts trying to get it to shoot until I measured it, and started to load to compensate. The Swede was designed for 160 gr bullets, thus the large amount of freebore.