Set up your parts on a bench so that they are roughly where they would be in relation to each other in the gun.
Look at how the trigger sear is, in relation to the bolt.
Where they fit together, controls how much pull it takes to pull them apart to fire it. Between the shape of the edge of the bolt and the sear surface of the trigger, they have to be adjusted to give the pull you need or want. It's strictly a "Go Slow" operation, as it's tough to put the metal back on. The trigger sear is case hardened, too, or at least the ones I have are. The bolt surface is like to be the one to look at as far as stoning or filing is concerned.
Take it to a 'Smith, if you are not up to it.
Cheers
Trev