In this work we study the dependence of the fully differential cross sections (FDCS) for single ionization of He by 100 MeV/amu C6+ on the momentum transferred by the projectile to the target. Three dimensional plots of the FDCS are used to illustrate how the different configurations contribute when the theoretical results are convoluted over the experimental uncertainties. This convolution is shown to be essential in order to properly reproduce the measured data.