The best available Modern Factory Rifle in 6.5x55 is the one you like best. I own in 6.5x55 a CZ 550FS, Winchester Featherweight M70, Husqvarna, and just bought a Tikka T-3 Hunter (one of the smoothest factory bolts I seen in a long time).
The bottom line is that the cartridge is the real star! Oh, I'd love to have a Sako Bavarian Carbine in 6.5x55 some day, but the reality is that they are all good picks. Its similar to a Football Player dating most of the Cheer Leaders- They are all beauties, so you just need to find the one you like the best and are most comfortable with.
