You need to measure how much you dialed up and you need to measure how much it moved over.

View attachment 7196233
View attachment 7196231
So the amount dialed up is the side adjacent to the angle we are after, the amount it moved over horizontally instead of perfectly vertical is side opposite of the angle. With those two known measurements you can figure out the angle via the tangent function.

If youre set up at 100 yards lets say you dialed the 10 mils, at 100 yards that would equate to 36 inches. If it moved over .1 mils in that distance then thats .36 inches .

tan( θ ) = (.36/36)

θ = tan^-1 (.36/36)

θ =

**.5729°**
Now... are you really sure that it moved .1 mils over or is it possible that you made a mistake or that the equipment shifted a tad? Because Im more inclined to blame the operator over a .1 shift than the scope. And even still, half a degree is nothing.