The Remington has a hammer spring tension screw in the front of the grip frame that can be used to change the tension on the hammer spring. I don't know about how to reduce the spring tension on the 1860 without actually grinding it narrower, which works but it's easy to ruin the spring if you're not careful.
In mec's book,PERCUSSION PISTOLS AND REVOLVERS, he describes putting a small amount of epoxy in the full cock notch on the hammer to limit the amount of engagement the trigger gets, thereby reducing the trigger pull without altering any of the bearing surfaces.
You might consider getting a copy of the book, you won't be sorry.
Steve