  We present results of a complete integral field survey of the bright SNR N49
in the LMC, obtained with the WiFeS instrument mounted on the ANU 2.3m
telescope at Siding Spring Observatory. From theoretical shock modelling with
the new MAPPINGS 5.1 code we have, for the first time, subjected the optical Fe
emission line spectrum of a supernova remnant to a detailed abundance and
dynamical analysis covering 8 separate stages of ionisation. This allows us to
derive the dust depletion factors as a function of ionisation stage. We have
shown that there is substantial (30% - 90%) destruction of Fe-bearing dust
grains in these fast shocks ($v_s \sim 250$ km/s), and we have confirmed that
the dominant dust destruction is through the non-thermal sputtering and
grain-grain collision mechanisms developed in a number of theoretical works.
