My method of doing the main spring is to screw the screw out until it doesn't fire. Turn it in a 1/2 turn at a time until it fires every time. Tighten screw counting 1/2 turns till tight. Remove screw and measure. A full turn of a 32 to the inch screw is .0273. Remove .0135 for every 1/2 turn needed to tighten leaving tip of screw slightly rounded. Install, tighten and test. You can buy all the 8/32 screws, with a variety of heads, you need at an Ace hardware that has a Gun Screw collection if you want to leave your original screw stock.
Changing out the rebound slide spring helps too. Just make sure it snaps the trigger back firmly every time.
Making sure the hammer, trigger and rebound slide bosses have no high spots and the hammer does not drag on frame helps to. Smooth beats light.
I got all wrapped up in getting a better trigger. Then figured out the very best thing to do was become a better trigger puller.
Unless the trigger has hard spots or is really hard, a few pounds of pull should not be a problem for a strong finger using a firm grip.