  We present calculations for the $c$-coefficients of the isobaric mass
multiplet equation for nuclei from $A=42$ to $A=54$ based on input from three
realistic nucleon-nucleon interactions. We demonstrate that there is a clear
dependence on the short-ranged charge-symmetry breaking (CSB) part of the
strong interaction and that there is significant disagreement in the CSB part
between the commonly used CD-Bonn, N$^3$LO, and Argonne V18 nucleon-nucleon
interactions. In addition, we show that all three interactions give a CSB
contribution to the $c$-coefficient that is too large when compared to
experiment.
