It'll loosen up a little with some shooting as VV suggests above. Take it out for a day of trap a couple of times.
Meanwhile it would be VERY easy to slick it up TOO much if sanding and polishing is not done with care.
One thing I can vouch for is that the mainsprings are far stronger than they need to be. I converted a Baikal full length SxS to a coach gun to use in Cowboy Action and the barrels wanted to spring closed due to the mainsprings. I opened the gun up and ground a fair amount off the main springs. This both softened the opening pressure needed, let it stay open while I loaded it and at the same time lightened up the trigger pull nicely. It still sets off all the ammo I've ever shot from it. So that's one option.
The mainsprings are not easy to get to. They are just about the last things to come out of the receiver before you're left with no two parts connected to any other. So unless you're pretty decent at home gunsmithing it's going to mean a trip to a gunsmith.