I swear by Thunder Heads 100gr. a couple of years ago I tried spitfires. I was on a urban doe only hunt and shot a mature doe that stood 6 yards from the base of the tree I was in. My arrow entered just behind and a little high of her shoulder. She ran off with about 12 inches of arrow sticking out. Later that same day another doe stood in the exact same spot. I shot her in the exact same spot with the exact same set up, beman 400 with a spitfire broad head. She went about 50 yards and expired. I looked for the first doe for hours and never found her. The obvious deduction here is the spit fire never opened on the first deer. This in my opinion is not worth the risk. I will stick with the fixed blades.