All it takes is 1 time for a mechanical to not open and you will kick yourself for not using fixed. If you can't get a fixed bh to group right then your bow is out of tune. I perfectly tuned bow will shoot a fixed bh exactly where the field point goes. I suggest a fixed. I wouldn't buy something that is not 100% opening everytime, especially when they make such good fixed. Just my opinions. Thunderhead or Muzzy.