I had the same conversation just the other day with one of our resident model air craft guy's.
The gyro that you put a thread in and spin like a spining top may work,but you would be adding the string to the rifle every standing lane.
The gyro's that the helicopter's use work on servo's with a direct link to the control's on the model,so they will not have any effect on the rifle.
Interesting idea though.
About as much use at field target , as a life guard at the Olympic swimming pool.