US Patent 10036622 Barrel measuring device

A measuring device includes a housing and a caliper positioned inside the housing. The housing has a proximal end and a distal end and defines an axis from the proximal end to the distal end. The caliper includes a first measurement probe extending out of the housing in a first direction, a second measurement probe adjustably coupled to the first measurement probe, the second measurement probe extending out of the housing in a second direction that is substantially opposite of the first direction, and measurement circuitry configured for transmitting a measurement signal based on the relative positions of the first and second measurement probes.