Re: RRA 2-stage trigger - first stage a little gritty
Try some 400 grit lapping compound (valve grinding compound) you can get at most auto parts stores. Use it only on the forward surface of the sear hook and its mating surface on the hammer. Cycle the parts a hundred times or two (dryfire) but be sure the hammer is dampened from smacking the bolt catch.
Be sured to clean it off thoroughly after you're done.