The front sight post on an AR-15 type flattop is invisible for all practical purposes when looking through a scope. No need to have a flip-up or removable front to use magnification. With lower powered scopes you may see a shadow, and with higher powered scopes your clarity and resolution is a bit degraded, but for scope testing or informal plinking you don't need to be overly concerned. If you want to swap for a flip-up, consider the Troy Industries sights. Rears are available also.