I had just the opposite happen. 2 years ago I was using Wasp Jak Hammers and on two shots at the same buck and 1 shot on a nice doe the blades opened in flight giving such bad arrow flight that all three shots weren't even close. So when I got home I tested the heads on my targets and the blades opened in flight every time. So this is why I'llnever shot anything but Muzzy's from now on.