It may not be the firearm or the sights. Many things can contribute to inaccurate and inconsistent shots such as stance, arm position and posture. More often, it’s attributable to what happened during the moment you pull the trigger.
This Handgun Chart has been floating around the social media for years in one form or another. I even remember seeing it before Facebook, Twitter and Instagram. Somewhere in my storage I think there may be an original printed paper version from a handgun class.
Use this and practice, practice, practice!