I would try a Wolff spring kit first, cheap and easy to put in and then if that isn't good enough... polish the mating surfaces of the moving internals, not the sear. There are videos on youtube.
I used to think like you that 250 yards was far, then I went to South Dakota antelope hunting. The guide looked at me like I was stupid when I said I had never shot at an animal at 400 yards... they were very spooky in 2011 and that was the closest shot I got... finally scored after I settled...