As I've posted under the gunsmithing thread, I have to replace the firing pin rivet on my Colt Single Action Army. My NRA book of firearms disassembly does not show the firing pin arrangement like my gun has.
My firing pin has a vertical spring with a detent ball top and bottom, this just ahead of the hole for the firing pin rivet. I assume this just provides a little play for centering the firing pin in the firing pin bushing when fired.
The view in my NRA book would seem to indicate the firing pin is rigidly mounted.