This is a spring loaded dart made of common items found in my local hardware store. My son and I saw something similar to this on a National Geographic special about the Chinese weapons. I don't remember what they actually called it, but from what I remember it was considered to be an assassin weapon. A low powered spring loaded dart that was typically dipped in poison. The weapon was easily concealed, and powerful enough to break the skin which in turn administered the poison. My version will shoot about 35 feet. I imagine that if I put a tip on the dart it would travel further due to aerodynamics.
Step 1: Material and Tools
1 - Shut off valve with chrome sleeve
1 - Short length of 1/2" copper tubing (2-3/4" long)
1 - 1/2" copper cap
1 - Strike plate
1 - Washer #10 I think
2 - Set screws 6-32 thread 1/8" long
1 - Length of aluminum solid tube 1/4" diameter
2 - Springs (#11 at my hardware store)
2 - Bronze bushing (5/8"O.D. 1/2" I.D.)
2 - Bronze bushing (1/2"O.D. 3/8" I.D.) Not pictured sorry
2 - Bronze bushing (3/8"O.D. 1/4" I.D.)
1 - tube of Locktite
Step 2: Construction Begins
Then I took the bronze bearings and slid them inside each other to make 1 long bearing with 5/8" O.D. and 1/4" I.D. I slid this bearing inside the chrome tube and soldered in place at the end of the tube.