Obtuned, glad you brough it up.....
Don't forget the 6mm. From the 6BR to the 6mm Mystic (new toy, new toy), they are lots of fun to shoot as far as you want.
In any cal, you just want to get the bullets going from 2800 to 3000fps. There are many many ways to do this so pick your combo and enjoy.
Now the important question, how easy can you find bullets/components. Some of the most desireable bullets/components simply are not available in Canada with any degree of certainty. do some research and decide what works best for you.
Great bullets include:
6mm, 105gr Amax, 107gr MK, 105gr Berger. 115gr Berger/DTAC. 90ish gr Scenar, 87gr Vmax, lighter Bergers.
6.5mm 123/139gr Scenar, 130/140gr Berger, 142gr Sierra, 140gr Amax. Know zip about the 120ish MK's and Amax.
7mm 162gr Amax, 180gr Berger.
The larger the cal, the higher the cost, the higher the recoil, usually better ballistics. Sometimes better wear and tear. For general plinking you will not see much difference.
Jerry