Can anyone give me a estimate of what point of impact change I can expect at 50 and 100 yards with a 4" 45 LC ( nomianl 800 ft/s ) load if sighted in at 25 yards?

Just looking for a rough estimate.

It would all come down to bullet weight and actual velocity out of your gun. You need the Ballistic Chart for your load to get a good estimate, most of the major ammo manufactures websites have them for their loads.