Might as well go all out....
Use all thread. As it spins it travels. Cut a C02 cart bottom off to make a bell. When the spinner reaches the end of the all thread it rings the bell. Put the same bell on the other end. Now go the other direction. Count how many shots to ring the bell. Least number of shots to ring the bell wins.
Top spinner travels left, bottom travels right.
Another game idea... take turns shooting. You top, opponent bottom. First to ring bell wins.
EI, EI, OH yeah !!!