@Andreas JagerI bought a spring kit for my 1860 army, it came with a lightened main spring.
I doubled it atop the Pietta spring. No cap bunce that Ive seen yet.
I called the company I got the spring kit from and they told me they have stiffer springs and if I wanted to send mine back they would send me a stiffy.
Id already redesigned the one I had, so it was too late for that.
https://www.emf-company.com/store/pc/-26-1851-60-61-Trigger-Bolt-Spring-p1729.htm
Mr. Tremain's post also contains a link to a supplier for the same 'fix'