If the rangefinder/drop compensator in the scope was actually developed for the Dragunov, it is probably calibrated to 7N1 or 7N14 ammo (about 150 grains at a touch over 2700 FPS, the 7N14 was, from what I've read, developed to improve the armor penetration of the 7N1, so the projectile is slightly different, but they are otherwise the same cartridge, more or less). It may or may not work with 180 grain bullets. Only way to know for sure would be to work up some loads and give 'er a swing.