The only thing I could suggest is what is called a "walk back tuning" method. Take 3 broadhead tipped arrows, and shoot one at 10 yards with your 20 yard pin. Then back up to 20 yards and shoot the 2nd broadhead with your 20 yard pin. Lastly, back up to 30 yards and shoot the last broadhead at 30 yards with your 20 yard pin. You should see a grouping like this.

...............................
...............................
...............X..............
...............................
...............................
...............X..............
...............................
...............................
...............X..............
...............................
...............................

If the arrow group starts looking like it's going diagonal, then you definitely have tuning issues.