Hey FC, im just sticking up for the much-maligned Mosin
I’ve only shot surplus or PPU brass cased ammo out of my Mosins. Definitely, meticulous cleaning is important. The asphaltene residue of the Soviet preservative, which is the non-volatile difficult to dissolve fraction that gets left behind, is quite sticky. I clean thoroughly with solvent (WD-40, Remoil, so oily solvents), swabs and wood picks, then lube the lugs and races heavily with a high viscosity oil before my first time shooting a particular Mosin to let the heat and mechanical friction help dislodge any more residue, then clean again and lube lightly.
That said, I freely admit a good condition Mauser action is easier to operate than an equivalent condition Mosin