When you see differing accuracy with broadheads the spine of the arrow is not a bad place to look. When the arrow comes off the bow it will flex some. With a broadhead, and especially a fixed head, that is not an uncommon place to initiate planing and if you have someone standing behind you watching they can see that. Removing the fletching and shooting bare shaft with field points of the same weight can be informative. If you cannot group them very tightly try turning the nock a third of a turn to each fletch when you refletch and see if the spine of the arrow is affecting your shots. If your arrows are well balanced you should be able to shoot pretty tight groups bare shaft. You can sometimes solve the problem of an arrow that won't quite group like this by finding where it needs the nock aligned.
