I mounted a scope and developed a load for a friend of mine. I’m at 850 feet of elevation. The gun was shooting great when he left. I had it zeroed at 100 yards. He got to his elk hunt today. He is 2 inches low at 100 yards and is at 7200 feet. He dialed the correct moa and tried at 350. He his 6 inches low. He’s the clinker, there are 6 guys on this trip and everyone of them is seeing the same thing. Higher elevation shot be less bullet drop but not in this case. The gun is a tikka 300 win mag, h1000 powder, 200 gr eld-x. Temps are similar to when we shot here. Anyone have any ideas?