First try different bullet weights, assuming you are shooting 230 gr ball ammo and I could be way off on that but bear with me. Try a box of 200 gr and a box of 180 grain. Put the tall post on and if need be grind it off to make your chosen ammo shoot to point of aim at 25 yards. One of those three bullet weights will be closer to where you want to be and your gun will undoubtedly shoot each of them well but one of them will be a bit tighter than the rest. If it is reliable in your gun that is your ammo from now on for that gun.
Standard square notch and post is the most accurate sight, the 3 dot sight loses a wee bit on fine accuracy but is quicker to acquire for most people and for self defense and fast shooting exercises could be your chosen preference.
I prefer the target sights for hunting and make do with them for speed shooting but that is me.
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