6-21-07 UPDATE: Added an SCR into the circuit (new button; the old one short-circuited). Details on the SCR on step 3.
Step 1: Enter at your own risk!
Looking back on this instructable, I realize there are numerous fatal flaws in the design. Some recommendations:
-A more stable (and much faster and effective) CHARGER
-At the current time, I'm pretty sure the SCR in this design will, *ahem*, explode the way it is implemented. One with higher voltage/current abs. max ratings is necessary, or you can use a technique called "Paralleling, Anode to Anode, Gate to Gate, and Cathode to Cathode" (I'm quoting an excellent site for coilgun reference HERE ). Pardon my engineering but I think it was about 15 when I did this instructable.
Good luck and have fun!