I have been messing with a Beta version of the new CameraAxe the last few days. It is a great piece of work for projectile work.
Unlike my home-brew trigger/delay, the Axe with the proper sensor will actually measure the speed of the pellet and put it right were you want it to go. The accuracy appears to be about +/- 0.1 inch.
I had tried a few times before to capture the moment that a pellet hits a watch, but never got lucky. With the Axe I got two out of three.