My first one was a shooting chrony. It was a certifiable POS. Nothing but trouble. I bought the Prochrono and never looked back. It works right, 1st time, every time.
My suggestion is get one with the electronics separate from the sensors. The sensors are relatively cheap in the event of an accident. PACT and CED both are like this.
To reduce the chance of accident, put a target behind the screen so there is a good place for the bullets to go aside from the sensors.