Expensive brass, minimal factory ammo, kicks more than a 6.5mm alternative.
Arguably 6.5x55, 6.5 Creedmoor or .260 will suit that purpose better as they are all more than capable of 600 yards and more.
260 and 6.5x55 are available in all Tikka models from factory, and a few available in 6.5 Creedmoor.
6.5x55 has a lot of factory ammo available, and lots of brass available. The 6.5CM and 260 have Lapua brass that doesn't need to re resized unlike 284 (from 6.5-284).
260 and 6.5CM will fit a short action (not that you will save any weight using a Tikka T3), and all three kick less than a 284.
Nothing wrong with the 284 at all, but within 600yards there are plenty of caliber options that will do the job, even a standard 7mm08 will do that easily.
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