Mainspring adjustment?

Is there a way to reduce mainspring strength? This lock works fine, sparks well but the spring is pretty damn stiff - can it be "softened" up a bit?

Narrowing it by careful grinding will lighten it proportionally. 20% reduction in width will reduce force by 20%.

thinning it will reduce strength logarithmically. A 20% reduction in thickness will reduce strength by 36%. A 30% reduction in thickness will reduce strength by 51%. Be careful if you choose to thin it.
Some Harpers Ferry locks are bashers and the trick is to change the angle of the cock so the flint slices more than bangs the frizzen head on. To do this cut a gap in the front of the “O” in the reinforced cock, bend it closed, then weld or braze.

I like em tough. Just don't get too hot, as rich says, "CAREFUL" grinding.

You may wish to file if you can instead of grind. Grinding generates heat pretty quickly, which may affect the spring temper. Another source of spring weakening.

If it ain't broke, don't fix it!

If you grind, make sure you always go length ways, never across. Polish/emery the ground area to smooth. When I grind and there is a concern for too much heat, my hand is the guide. If it heats up above comfort, I quench and then continue. If it sparks good and in the pan without eating flints I would not do anything with the spring.
Flintlocklar

I draw file the inside of the mainspring to make it weaker, this way I have alot of control and no gouging. I follow up with various grits of sandpaper on a wood block and finish with emery cloth.