I bought a remington sendero in 300SAUM and I can load 150 and 165 grain loads, shoot 5 shot groups at 100 yards with the 1st 2 shots almost touching and the last 3 shots will move around 1 inch or so. Maybe its a bullet seating issue ? Any help would be greatly appreciated.

check to make sure all the screws are tight. My friend had the same problem and found out the srew that held the action to the stock was loose.