It is difficult to model with friction coefficients in this case, because the normal force is dependent on very small changes in dimensions and material strengths that your software may or may not support. Friction is by no means as easy as it is in the text books. The basic idea is find the force normal to the friction surface in question and calculate the coefficient with the friction equation.
It may be more accurate and easier to just iterate to a solution. First you guess at a friction coefficient, insert it into your simulation, run your simulation, see if your result is higher or lower than amount you measured, then guess a new value and repeat until you feel that you are are close enough to your measured value.