A pair of spinning wheels 1.5 meters apart is placed in the path of a bullet. A bullet is fired with the wheels stationary for reference position, and fired again with the wheels spinning at a known speed. The second wheel will rotate more than the first as the bullet crosses the gap between them. When the angles between the reference holes and the second holes are compared, the speed of the bullet can be determined.  The balloon is used to show when the bullet has passed through both disks. This video was shot with a Phantom v7.1 high speed video camera (donated by Vision Research Inc.) at approximately 7000 frames per second. The frame data can be seen at the bottom of the screen. Special thanks to Dr. Jim Bales, MIT Edgerton Center.