My bow is perfectly tuned to shoot 100gr field points
Chances are, it's not the bow, but the arrows that are not perfectly tuned. Muzzys shoot right where they're supposed to if everything (especially the arrows) are perfectly tuned. Arrow tuning, includes spine tuning, bare shaft tuning, spin tuning and proper cutting techniques. Very, very few hunters tune their arrows for a perfect match to their bow.
You can still kill deer with less than perfectly tuned setups, but that's not how I prefer to hunt. Perfect arrow flight will resist planing in wind, cut down on deflections off twigs and will be overall more forgiving. Add in greater penetration potential and I have all the reasons needed to get it right.
I'm currently shooting Muzzy Phantoms at 220 gr and they fly perfectly with my equally weighted field tips. I've also not had trouble with other models of Muzzys in the past.