thats a pretty nice looking rifle you have, and night force makes a really nice scope but are too expensive for me to afford. I think europeans are a little misinformed and have the wrong idea, not all americans have SAKO rifles and Swarovski scopes. for most of us we can only afford remington rifles and simmons and bushnell scopes and maybe leupolds if we are a little more fortunate. Just because we are American it doesnt mean we are rich with endless amounts of money to spend.

The 243 is not a bad long range varmint caliber, if i were you i would research it some more I dont know what powders you have access to but the right powder/bullet combination should give you plenty of down range energy for 400 to 500 meter shots. I use a savage model 12 varminter in 22-250 caliber with a bushnell banner 4-12x40mm and find my handloads to be plenty powerful for coyotes even as far as 600 meters. My handload is a 50 grain V-max over 36 grains of hodgdon H4895, through my chronograph its pushing and average velocity of 3,754 fps the estimated muzzle energy is 1540 ft lbs. at 500 meters I estimate the energy is around 500 ft lbs still which is more then enough hit to take a coyote down.

If you can get hodgdon powders I would take a look at their website for some load data http://www.hodgdon.com/data/rifle/index.php

I looked at some 6.5-284 load data , to be dead honest that cartridge wont give you any real advantage over a 243. You would be better off with a 6.5x55mm swedish over the 6.5-284 cartridge. Id look at the 250/3000 savage or 257 roberts those two have a real advantage over a 243 without getting into the large game cartridges. But I dont know what you can get there is russia. honestly i would just stick with the 243.