This study focuses on toroidal elements having dimensions 3.1 × 1.5 × 1.4 mm and composition, mol.%: 37.6 Fe2O3, 38.1 MnO, 9.3 MgO, 11.7 ZnO, 3.3 CaO. It is shown that increase of the innerto-outer diameter ratio of the toroids leads to higher squareness of the hysteresis loop. The geometry of the samples and gradients of coercive force H c caused by structural heterogeneity influence the shape and squareness of the hysteresis loop. In the absence of oxidation, the surface layers of elements have lower H C than the inner ones because their magnetic reversal begins in weaker fields, promoting smooth transition from the horizontal to descending section of the hysteresis loop. The nonequilibrium oxidation of elements cooled down to the hardening temperature leads to an increase in H c: to a greater extent on the surface and to a smaller extent inside the toroids. As a result, the upper half of the descending branch of the hysteresis loop becomes steeper, while the lower half more shallow. Isothermal holding at the hardening temperature reduces the gradients of H c and the squareness of hysteresis loop.