If you've already acquired experience using good old iron sights to aim, then by now, you've figured out the limitations of backup iron sights. You've probably also acquired at least a small amount of knowledge about red dot sights. And you've decided you need to make the switch to a red dot for your long gun.
The Bushnell TRS-25 3MOA Red Dot Sight is the switch you need. It features a 3 MOA dot with adjustable elevation and windage and comes with a high-rise mount for that lower 1/3 cowitness. See below for more info.