I went out shooting today. Shot from 120 yards and 240 yards. At 120 I shot 14 shots in a 5inch group. Out to 240 yards, however, and I shot 3 shots within 1 inch. This seems really weird to me. I was shooting my Weatherby Vanguard 30-06 with fusion 150gr ammunition. What could cause this?

Also I shot the other day from 120 yards also but with federal 150gr and my group size was within 2inchs. Do you think my gun responds better to these bullets? What could another explanation be?