Why don't you show us the Italian military document that supports what YOU say.
These markings are not common but they are well known as has been pointed out by numerous members of this forum. As already pointed out, this symbol signifies the rifle has some association with the "Tiro a Segno Nazionale," the Italian National Shooting Organization, be it a prize awarded to a match winner or that it was produced specifically for competitions. Given that, it is to be expected to be of somewhat better quality, thus more accurate than the standard run of the mill rifle. It has not been claimed by anyone here that this is a sniper rifle, just better than most.