I shoot my Rocket Wolverines into a bow layered with insulation board. If I'm lucky enough to be able to pull it out, the blades are closed and the band is usually lost. But if I take out each layer of insulation I can see that the blades did open usually on the first layer. Try your broad head on an apple or orange with your broad head target behind it to stop it, you'll see that they open rather quickly and easily.