I shot a groups of muzzy mx3's and at 30 yards they shoot about 4" high but the groups is about 8" big. At 20 they hit about 1"-2" high and the groups is 3"-4".
I can group field point well. 20 yards 1"-2", 30 yards 2"-3.5", and 40 yards 3"-4". I only have 3 pins so 40 is my max, otherwise I would shoot 60+.
Your bow is out of tune or your arrow spine is way off. Broadheads, like barehafts, reveal flaws in the bows tune and arrow setup. Watch a video on broadhead tuning. I have shot MX-3's and they always grouped well.
It might. Remember if your arrow is not coming out straight it will wobble back and forth till it corrects itself. So worth trying. Also remember that your point of impact will change too. Try shooting a few broadheads and a few field points to see how they group and correct the rest based on that. Good luck.
Broadhead, paper, and walkback tuning will all help you to make sure your arrows are coming out of your bow straight. Your broadheads are planing and your vanes are unable to correct this. If you get your bow tuned properly, it will most definitely help your broadhead groups.
I'm actually in the process of tuning bow to the arrow. Just the same thing that Tim Gillingham does and he is a very successful hunter and one of the best competition shooters. After I can get to the shop to make two twists in yoke my paper tear will be a perfect bullet hole and my bare shafts will shoot together at 20 yards pefectly. After Tim emailed me he said it might be the fetching not being big enough to help stabilize the head. He told me to go with the 3" super spines for expandable heads. So broadhead tuning might be a little more challenging but I can get it done.
