The mainspring's only job is to capture energy and use that to crush the primer. You'll want to leave that at full power.
Barring an action job and thousands upon thousands of rounds through the gun. You can lighten the double action pull by installing a lighter rebound spring. 15 or 16 pound is the factory standard. 13-14 pounds is just about perfect. There is a trade off for going with the lighter rebound spring. The lighter you go the slower the trigger resets. Anything less than than 13 and it will be so slow it's noticeable.
Now the problem you run into by installing the lightened mainspring is you capture less energy and therefore have less to hit the primer with. That can lead to light strikes. You could combat that by installing a longer firing pin.
An enlightened zeal for the energy and efficiency of government will be stigmatized as the offspring of a temper fond of despotic power and hostile to the principles of liberty.
Alexander Hamilton, author of Federalist No. 1. 10/27/1787
Last edited by Jason D; 10-07-2012 at 18:39..