How about SLINGSHOT PAINTBALL!!

I don't believe that it is legal to use paintball guns while camping, so we used slingshots. It worked really well too! We even chrono'ed it to see how fast it was shooting. A paintball gun shoots around 280 feet per second and the slingshot only got to 216 fps. That is actually really good. Good enough to break skin (as shown below). So here are some pics: