An old 45 training trick we used in the military. Use a sharpened wood pencil that is about 4" long. Wrap 1" masking tape around the pencil until it just fits free in the bore, one wrap in front, just behind the taper, and one about 1.5" up from the eraser.
Hold the muzzle up, cock the hammer, level the gun and "shoot" (no ammo of course). The target is taped on a wall at "gun height". Draw a small aiming dot on the target and hold the muzzle about an inch away. Your groups will be about 3/4" low. Keep practicing until you can group 5 "shots" under 1/32". Be careful, the firing pin has enough energy to launch the pencil across the room.
Great way to spend a rainy day and it won't hurt the gun a bit! Then you can fill the tiny holes and paint the wall before the wife yells at you. (Subtle hint to use a board between the wall and target)