Capacitor Discharge Time Problem
It's not clear from your question, but it seems your are ignoring the inductance of your inductor, taking into account only its resistance.

A ideal capacitor "discharging" into a ideal inductor does NOT cause a simple exponential decay of the capacitor voltage, like would happen when discharging into a resistor.  Instead, you get a sine voltage.  With ideal components, the energy is continually sloshed back and forth between the capacitor and the inductor forever.  The voltage across the two parts, and the current thru them are both sines, but 90&deg; out of phase.

Discharging a capacitor into a inductor thru a SCR also gets interesting.  Remember that the SCR stays on as long as there is current thru it.  In the ideal capacitor/inductor case, the current builds up until the capacitor voltage is 0.  That is actually the point of maximum current.  The current then continues until the capacitor voltage is the negative of what it started out at.  At that point, the current starts to build up in the opposite direction.  This is where the SCR would turn off.

You actually have a capacitor, inductor, and resistor all in series.  The pure capacitor/inductor case causes a infinite sine.  Add a little resistance and you get a exponentially decaying sine.  When the resistance dominates the inductance, you get mostly the R/C exponential decay you seem to be assuming, but with wrinkles.  The resistor effectively adds damping.  Whether you get ringing or not depends on how damped the system is.

You can't ignore the (probably) significant inductance of your "coil".