I' m not sure I' d call it BAD news, but I find Spitfires to perform quite different than many swing open " Tip to rear" style mechanicals............For One, IMO they need more energy than the cutting diameter dictates due to the tension the retention clips place on the blades. They just don' t open very fast at all, and it takes some force to do so. I know any sharp broadhead in the boiler room will do the job as long as it " Gets there" , however if you want to reliably " Get Through" you should probably be shooting 65ft lbs of KE and over for the most reliable performance.
Now I' m not saying that some shots will not pass thru at lower energy levels, but if you want the MOST reliable performance, especially if you hit some ribs , thick back muscles, or nick a shoulder blade etc........keep the energy up. That goes for all heads really but especially this design.

Since they don' t open very fast, you can encounter " Bullet Hole" style entrance wounds.........I' ve shot 2 deer with a Spitfire and BOTH displayed that type of entrance. They did open inside and do a nice job but I totally prefer a mech that will give me as close to a full width entrance as possible. Just picture the type of blood trail that is possible if you have a tiny entrance wound high on the animal, with no exit? Not good. And remember you increase your odds of this as you head toward the lower end of the KE levels that are adequate for this head.

Pluses for this head?.........Quality of construction....its very nicely made (hate the clips, but the rest of the head is well made) Blades are nice and sharp right out of the package. Sharper than most.