You definately need a helical fletching. I used to use a straight fletch (didnt know any better) and I never could get my broadheads to fly right. Also make sure your bow is papertuned. I was having the same problem a few weeks ago with mine hitting low and right. I papertuned again (something must have moved) and now they are all dead on even at 40 yds.

Bring on the deer!

rick