The best aftermarket sights for all guns, IMO are the XS Big Dot night sights. There are many videos on you tube, as well as numerous reviews and recommendations for XS on here as well. Be cautioned, if you try them, you will find all your guns need need them.
Laws that forbid the carrying of arms... disarm only those who are neither inclined nor determined to commit crimes... Such laws make things worse for the assaulted and better for the assailants; they serve rather to encourage than to prevent homicides, for an unarmed man may be attacked with greater confidence than an armed man. -Thomas Jefferson's "Commonplace Book"