Lego!
 

I recently built a rubber band gun out of lego(i know, Im childish), at 8yds aiming 4ft high I can hit a 6in circle, it is made so a lego block bullet is posittioned in front of a thingy that pushes it till the block comes undone. A rubber band is put on back of the bullet, when the trigger moves back the thingy hits the block, and BOOM!!! I sniped my brother at 5yds,it would have been a head shot but his finger was in the way.
Minihuntur