I just installed a Holosun 507k on my Glock 43X MOS, using an adapter plate that is .058" thick. The back of the optic has a notch that seems to function as a rear iron sight, which is convenient because I can no longer get a sight picture with the factory rear sight.

But since the optic is sitting .058" higher than it "should be" with the adapter plate, do I need to increase the height of the front sight post by that same amount? I believe the OEM front blade is .165" so I was looking for something that is .223"; I found a Novak Designs product that is a thousandth of an inch off from that.

Am I thinking about this correctly? Note that I am not trying to get a co-witness with the red dot... I just want functional iron sights that I can see through the window, as a backup in case the optic were to fail.

Input would be appreciated. Thanks!

Dave Dawson can help you with that: Sight Calculator