Im really not sure what does this but two years back I had the same exact problem. I found out the field tips were my problem, I switched to 100 grain Slik Tip Points and they shoot exactly like my 100 grain broadheads. Good Luck!

as buck hunter said if your getting groups with them re sight your bow . just because the points are the same weight dont mean they are going to fly exactly the same as a field point .

I had this exact thing with 100 gr. Muzzys too. I found the grouping OK, just 8-10" low at each of my yardage points. So I just lowered my entire site apparatice to compensate. That way, all my pins stayed fixed, but my shots all came up at each distance. Of course, I marked the site so I can readily go from field point to broadhead as the situation requires. I still can't get the consistency with the Muzzys I can with FPs...but it gets me in the ring!

I have had different broadheads shoot both high and low of fieldtips. The NAP nitron's i use shoot the most like my field tips. If i remember correctly the muzzys were similarly low like yours, which is why i switched. Clay, that a fast hunting bow.

Goes to show the importance of not only practicing with field points, but also with your broadheads.