Nvy: The third shot business;many factory barrels will throw a third shot from heat.Not unusual at all.Those are pretty light contours for a 30 caliber magnum of any type.My 270 FW does not throw shots one to two minutes out when it heats;shots 3 and 4 stay in the group.Also, barrel heat may not be the issue.The 300 WSM we shot(like yours),loved the Fusion ammo,but shot as you described with other factory ammo....just the way it goes....
Besides, based on that group with the hornady bullets,it looks like your rifle is shooting fine.I don't expect one hole accuracy from a light sporter with factory barrel and tuning and chambered for a powerful cartridge like a 300 magnum;nice if you can get it,but not really likely.
There are lots of other things that cause "flyers"besides barrel heat.
Yours seem to like the Hornady;shoot it again but after three shots,shoot another 2-3,and watch how it groups.Do you handload?
