My search turned up the following:
Height of Back Up Iron Sights above rail
M16/M4/AR15 Iron Sights is 1.41"
HK416/M27 IAR Diopter Sights is 1.27"
FN SCAR 16/17 is 1.45"
Centerline of bore to Centerline of iron sights aperture
M16/M4/AR15 Iron Sights is 2.61"
HK416 Diopter Sights is 2.726"
FN SCAR 16/17 is 3.38"
Height of Back Up Iron Sights above rail
M16/M4/AR15 Iron Sights is 1.41"
HK416/M27 IAR Diopter Sights is 1.27"
FN SCAR 16/17 is 1.45"
Centerline of bore to Centerline of iron sights aperture
M16/M4/AR15 Iron Sights is 2.61"
HK416 Diopter Sights is 2.726"
FN SCAR 16/17 is 3.38"