57Fe Mössbauer spectrometry was carried out on high-energy ball-milled crystalline compounds in order to study the milling effect on the Lamb–Mössbauer factor f. A comparison between metallic (α-Fe) and ionic (r-FeF3) milled powders is proposed, evidencing different milling mechanisms. In the case of the ionic system, a notable enhancement of the f factor at 77 K is observed by freezing the powder into a resin. This suggests that, in addition to nanostructured aggregated particles, the milling procedure favours the obtention of isolated nanoparticles, the sizes of which are smaller than the critical size for the observation of the Mössbauer effect. In return, in the case of the metallic system, the absorption gain due to the embedding is much smaller, probably due to a better re-agglomeration of the metallic particles during the milling process.