Go to the northwest area. Select the open hunt area next to the bear mission and set the time to 9:00. Use the .338 magnum and take as much ammo as you can or use the 30-06 if you want to work toward 10 kills with it. Make sure to take as many rounds as you can hold because you dont want to run out. Only shoot at bears if you think you might run out.
Now run to every bear feeding area on the map. You will hear the bears before you get close enough to scare them. They will be in a red flower field. When you get close enough to hear them stop running and walk (if you have cover in front) or crouch and move until you see the bear. Make sure to tag him with the binoculars in case you miss so you can follow it. Once you kill it move to the next area until you have killed 3. Hopefully you will get lucky and they won't be too far apart.
I chose this area instead of the northeast because it is more open and easier to shoot the bears from a distance