The resistivity, ρ, of ceramic La_1-xCa_xMn_1-yFe_yO₃ with x = 0.3 and y = 0.0-0.09 is found to obey, between a temperature T_v ≈ 310-330 K and the ferromagnetic-to-paramagnetic transition temperature, T_C = 259-119 K (decreasing with y), the Shklovskii-Efros-type variable-range hopping conductivity law, ρ(T) = ρ₀(T) exp[(T₀/T)^1/2]. This behaviour is governed by generation of a soft Coulomb gap δ ≈ 0.42 eV in the density of localized states and a rigid gap δ(T) ≈ δ(T_v)(T/T_v)1/2 with δ(T_v) ≈ 0.16, 0.13 and 0.12 eV at y = 0.03, 0.07 and 0.09, respectively. Deviations from the square root dependence of δ(T), decreasing when y is increased, are observed as T → T_C. The prefactor of the resistivity follows the law ρ₀(T) ∼ T^m, where m changes from 9/2 at y = 0 to 5/2 in the investigated samples with y = 0.03, 0.07 and 0.09, which is connected to introduction of an additional fluctuating short-range potential by doping with Fe.