RE: I can't get groups with my broadheads
I suggest paper tuning your bow. Once you do that and get your bow tuned it'll likely shoot just about any broadhead.
IF you KNOW your bow is already tuned .... try different broadheads. Muzzy always shot good for me. Mechanicals are good - like the First Cut heads ..... but bottom line even mechanicals will not correct an improperly tuned bow.