Actually the ballistics of the semi-auto SVT and the PU are slightly different so the elevation cam has a slightly different cam. You can adjust the elevation knob as you mention but it will not change the cam. It will only set the rifle for 100 meters, or whatever your zero range is. SVT scopes were used on PUs, and SVT tubed scopes continued to be used on new PU production. If the scope was originally calibrated for the SVT, a cam was installed and marked CB for the PU ballistics. In the real world, the difference in ballistics is small. That is especially true if you are not using WW2 era LB ammo. Current LB is slightly different and the bullet base is different.