The processing map for hot working of cast Mg–3Sn–2Ca–0.4Al (TXA320) alloy has been validated using forging experiments to form a rib–web (cup) shaped component. Finite-element (FE) simulation has also been conducted to obtain the strain and strain rate variations in the components as well as the load–stroke curves. TXA320 has been successfully forged under optimum processing conditions (450 °C at press speeds of 1 and 0.1 mm s⁻¹) predicted by the processing map, where dynamic recrystallization (DRX) occurs. The microstructure obtained on these components revealed fully DRX grains and the average grain size has increased with increase in temperature. The load–stroke curves predicted by FE simulation of the forging process correlate well with experimental curves, although the simulated curves are slightly lower. Forging done in the flow instability regime of the processing map resulted in specimen fracture and the microstructure exhibited cracks at flow localization bands.