Hi, I start this thread saying that this is my first post on this forum and that I'm not english so I could do some grammar mistakes.
I'm working on a coil-gun, here's the circuit:

The problem is that I am not able to choose the right thyrsitor, I've tried with a BT151-650R, but it died.
I've measured the resistance through the fire circuit, and I got .2-.3 Ohms, then I calculated the max current I could get at 48V and I got 240 Amps.
Can you suggest me a cheap SCR which can meet circuit's specs?

 

You're firing the thyristor wrong, you need the Load L1,in the Anode leg, and a 1K resistor across the G/K terminals to prevent false triggering. The problem you have is the thyristor will Latch ON with DC.

You would be better charging a Capacitor with the DC and use that as the firing voltage, then when capacitor is discharged, the thyristor will turn off ready for the next pulse.

 

What is the purpose of this circuit?