A discrepancy between predicted and measured neutron rates on MAST using TRANSP/NUBEAM was observed. Further causes of this discrepancy are here studied by means of TRANSP/NUBEAM and ASCOT/BBNBI simulations. Gyro-Orbit simulations resulted in an approximately 20 % reduction of the fast ion density compare to the Guiding Center with TRANSP/NUBEAM and ASCOT/BBNBI. DRESS was used to calculate the neutron rate at the Neutron Camera detector’s location showing how the discrepancy is considerably reduced, with now the correction factor, used to match experimental and predicted neutron rates, being around 0.9.