If you can keep the rifle pretty steady, you can get a pretty good idea of where the bore is pointed by removing the bolt. Look down the bore and find the target. Keep the rifle steady and move your eye upwards and see where the crosshairs are. Adjust scope accordingly. Just keep checking until where the bore is pointed seems to match the crosshairs. When they do, try a shot and make further adjustments.
I have used laser bore sighters and been way off, like farther off than I would have been doing this to get on paper from 50 yards.