Ok,, I'm a little confused here.
It may be due to I'm wondering about a Double Action Redhawk that's a convertible. Two cylinders?
But,, w/o me going to dig out a Redhawk,, if the firing pin is mounted in the frame like the Blackhawks,, the 2" long pin is used to drive out the existing firing pin retaining pin. It's a pin driven in the frame across the sides,, to hold the parts in place.
Look inside the cylinder window,, for a hole,, the same size as the 2" pin. Look on the outside of the frame,, in aligned with the hole,, and you should BARELY see the head of the pin,, flush with the frame.
If light strikes are an issue,, I'd replace the mainspring first,,, try that,, and if you still have light strikes,, switch to Federal primers.
I'd do these two things before I'd attempt a firing pin replacement.