A quick way to check for barrel indexing is to remove the rear sight and leave the front sight protector in place, then invert the rifle on a sheet of glass. If there's a rocking motion it shows that the barrel is off index.
The front sight protector that is catywhampus, like the one that is currently installed, isn't good for this check. In this case the bent protector may be leading the eye to believe that the barrel is somewhat off index.
The eyeball is a pretty good check for index. If a front sight is off index to the extent that it matters, it will be seen to be off. When barreling Garands I use horizontal angles on the gas cylinder and rear sight surface of the receiver to establish vertical index. When the angles appear to be parallel, they are and the barrel is correctly indexed. I cross check this with an angle finder and find that it always confirms what the eyeball comparison has shown.