I sighted in my 300wby mag. last month and was dead onat 100yds (2 inches high, all holes touching). So I went out today and my shots were all over. I was unable to group them, and every time I thought I was on the pattern would change. Could it be my scope, the mounts, the weather,(it was very hot outside)? I left very discouraged, and down 50$ in ammo as well. Could you guys please provide some ideas!! Thanks