If you were going to file the rear sight rather than get a higher front, then don't forget that it isn't just a matter of making the notch deeper, but you also have to file the top of the sight. This is because the top of the foresight aligns with the top of the rear sight.
Personally though, filing the rear sight is not something I'd do (or more accurately, not something I'd do again). It may just be me, but it is difficult to do a good job of it. If you know how high you are at 100, and know your sight radius, it is easy to calculate exactly how much higher the front needs to be. You can then go and get one or make one, or have one made, which is exactly that high, rather than cut and try and fart around with files.
FWIW these rifles were shot in at the factory, and supplied with a test target, so I'd first see if there was some other reason for the rifle shooting high. But that is just me. It could be as simple as them using a different load, or the way you "see" the sights.
