I do not have a centerfire rifle with sights like shown - I just got a 7x57 BSA "sporter" rifle with a barrel mounted rear sight standing leaf marked "100", and then two folding leaves - one marked "200" and one marked "300". Back in the day, with the old Cooey .22 in the pasture, I did not know about changing sights - it was as it was - "held off" to hit what I intended to hit - aim above the gopher, if it was a long ways away. My Dad used to use phrases like "take a fine bead" - as if there was a way to alter your aiming point by how much front sight bead that you could see in the rear sight notch. What is the shooter going to do if he guesstimates the game is at 250 yards - use the 200 leaf or the 300 leaf - either way, he is probable to want to be able to "hold off" a bit from where he wants to hit. Is not target shooting or shooting for groups or for points - is usually about getting one good kill shot - make it or do not make it.