O yes! The icing on the cake!!
I found small diameter (compression) coil springs on ebay (nickcwizardscx) which I used for the actuator rods for the brake system (see photo), but would also look good on that firing mechanism! Sizes 1.5 to 25.4mm diameter are available in 300 or 600mm lengths. I used the 2.4 and 3.0mm varieties.
Cheers,
Marcus