I killed a buck last year with a phantom and the carnage it produced was awesome.
With that said, the Phantom is a big broadhead with a lot of wind catching wings on it. If you are having troubles getting 3 blade muzzys to group I don't thing the Phantom is the answer your looking for.
In my experience the Stingers are more of what your after and that is coming from someone who shoots both Stingers and Phantoms.