Shooters of RBs please note: the sighting notch at the end of the sight leaf has a slope on the far end. The vertical surface should be towards the shooter, to provide a sharper sight picture. As shown in the picture provided by Butlersrangers. Please look at any Enfield muzzle-loader or BPCR rifle to confirm the prevalence of this sensible arrangement.
Unfortunately, RBs appear to have been so messed about with in their service lives that a lot of them have the end of the backsight leaf, and thus the sloping face, towards the shooter, which produces an awful sight picture with a lot of reflected light on the leaf. Maybe a misguided alteration - or even specification - on the assumption (false) that it would be advantageous to have the notch as close as possible to the shooters eyes?
If you want to get better results from your RB, make sure that the vertical face is towards your eyes. And since any "bluing" will have disappeared a century or so ago, blacken it to improve contrast.