A firearm sensor system includes one or more sensor groups and a data storage device. Each of the sensor groups is configured for attachment to a firearm. One of the sensor groups includes a sensor for measuring a position of a firearm bolt relative to a start position of the bolt, and a wireless transmission component for wirelessly transmitting the sensor data. The data storage device includes a computer-readable medium having an executable application stored on the computer-readable medium. The application, when executed on a computing device, receives data from the sensor group via a wireless communication system and presents the data in a user interface displayed on a monitor. In one embodiment, the sensor includes a spring force sensor coupled to a bolt return spring on the firearm.