How do you adjust the sights on a 30-40 krag?

I have an 1896 .30-40 carbine, and have found that the only way I have an ajustment to the horizontal bullet strike on the target is to just "tap" the front sight in the direction you want the bullet to strike the target. My rifle is "sighted in" to be on target at 200 yards when using 180 gr. "core-loks". I figured the Army had taken this into consideration when having the rear sight set for 300yard battle sights. I hold the front sight at the 6 oclock position on a 6" Bulls Eye at 200 yards, and, even at my age of 69, manage to get acceptable results in the "bulls-eye". Plenty good for "White Tails" in this area. ( Dont figure these carbines and rifles were intended for target rifles).