Prototyping the cannon was very difficult, almost like a nightmare. Because here we're dealing with 50A going through a coil, and we need to turn the current on and off in microseconds. And as you should know from inductor theory 101, if you change the rate of current in an inductor, a voltage will be induced in the circuit. That was the problem that I was having, a huge spike of voltage was appearing in the Drain of the MOSFET, killing it instantly(I killed about 20 MOSFETs during prototyping). I didn't know that, because at that time, I had an old analog scope, incapable of doing single shot capture, and I thought that it wasn't the problem, because I was using a regular 1N4007 flyback diode to prevent voltage spikes, and it wasn't working . But when I tried the circuit with a digital scope I saw that voltage spike appearing, and I thought that I needed to change that slow diode with a faster shottky diode. So I replaced the 1N4007 with a 1N5822, and it worked! Since then, no poor MOSFETs have been killed by the voltage spikes and the gun is firing perfectly.