Epitaxial films of Hg1-xMnxTe (MMT) have been grown by direct alloy growth MOVPE. Perfection of layers grown on CdTe buffered GaAs, and unbuffered CdZnTe substrates has been assessed by double axis X-ray diffraction. No significant difference was observed in the rocking curve full width at half maximum (FWHM) between layers grown on the two types of substrate. Rocking curves taken as a function of position across the layer showed substantial variation, there being a very good correlation between layer thickness determined from the intensity of the substrate peak, layer rocking curve FWHM and Mn composition determined from the substrate and layer peak splitting. The contour maps of these parameters are discussed in terms of depletion of the DIPTe precursor.