I'm looking into making a chronograph to measure an airsoft rifles output. The speed ranges from 300-500fps, with up to 60 rounds per second. I would like to measure projectile speed, as well as how many rounds fired. I was looking at this photo interrupter (http://www.sparkfun.com/products/9299) from Sparkfun, but I'm not sure if it would be best suited for the application. Is there a better product available? Guidance would be appreciated.