As ticketed machinist of over twenty years and amature gunsmith with a very good grasp of heat treatment and metallurgy I hope nobody takes the above post seriously. Building firearm parts with mild steel and welding springs with coat hangers is not only unsafe but boarders on foolish.
Truck repair shops can easily De arch springs, had them done in the past ,some times I could wait for them 20 min, if you have them separated, they have a suspension specialist this is what he does and builds custom spring sets ,you tell him how much you want to lower and he gets it the 1st time every time