It wasn't the scope power, 7x is fine for that shot...
I use 3x9 scopes and usually I will set it at 4.5-5x in the woods...Over our soybean fields in eastern NC I typically have it on 7x and then move it to 9x if needed...That being said, I killed a buck this year at 257 yards with the scope on 7x and the evening before I killed another at about 50 yards at 7x as well...
Remember back in Jack O'Connors day a 4x was considered fine for everything...