The mainspring on my Pietta 1860 Army broke.
I called Traditions, they sent me a new main spring for free.
It was slightly bigger than the previous spring. It was too powerful, hard to cock, seemed like it struck too hard.
I got out my second-favorite gunsmithing tool, the Makita belt sander.
BE SURE to use a fine-grit belt, 80 or smaller.
I held the spring in my hand, this made sure not to over heat it.
I ground off both edges of the main spring, about 10 percent reduction in metal.
This caused a 10 per cent reduction in power of the spring, it works perfectly now.