three pound is about as good as it gets. Jard makes a "drop in" trigger for the X-Bolt, can be ordered with a very light pull. I would be safe and go this route. close your bolt really fast and hard (empty gun of course) make sure the sear holds, also drop it from about 6" on the butt to make sure it holds. I wouldn't leave the screw out.
"I ain't here for a long time, I'm here for a good time"
King George Strait