Hi,
i`ve done the file down method and i can say that the graduation on my rifle didnt really work. For an example the 300m was perfect for 100m the 500m worked at 300m ( the shots hits only 5 cm lower) but no one of the others fits for any distance. I bought a higher front blade and it worked with the 400m at 100m and the 600m was perfect at 300m. I think the better solution is to buy an higher frontsight blade and leave the original one as it is.
Regards
Gunner