Force meter
A force meter is an instrument to measure the magnitude of a force. This is often just a spring contained within a cylinder that has a scale to mark the extension of the spring produced by the force. In the International System of Units, the unit of force is the newton (symbol N). A force meter that measures force in newtons may be referred to as a newtonmeter.
International Practical Shooting Confederation
The official unit used for the power factor is the imperial unit "kilo grain feet per second" (kgr·ft/s). "Grain feet per second" (gr·ft/s) can be obtained by measuring the "mass" in grain (gr) (equal to pound), and "velocity" in feet per second (ft/s), but since their product yields a very large number it is common to multiply by a factor of , obtaining the power factor in ""kilo" grain feet per second" instead.