coil gun

I am pulsing a 38mH coil (16 AWG wire wrapped around a small tube) with a IRFB4115pbf MOSFET at 66.6v (3 lipo 5200mAH "50C" battery's in series). It's a lot of juice! Using Lt spice I simulated this and found that the voltage spikes can reach up to 20kv. I am trying to figure out if I should use...

Hello, I have been making circuits as a hobby for 2 years now mainly focusing on trying to make a coil gun, and tried and failed 7 times now, and I am in desperate need of help with the circuit, if you see anything wrong with my diagram please respond as soon as possible. I bought most of the...