jrdudas,
For a several generations now, nickel plated .38 special/.357 magnum revolver cartridges have been popular for law enforcement use for two big reasons: They are less likely to corrode while stored in belt loops and cartridge boxes, or in adverse conitions (high humidity, prolonged temperature extremes, etc) and they give easier extraction when fired. Both can be life savers when guns are carried for serious use.
These are also advantages when hunting, competitive target shooting, or serious defensive use.
For reloaders and users of reloaded ammunition, nickle-plated cases do have a disadvantage too. After several reload cycles, the nickle plating tends to flake and peel, especially at the case mouth were it is crimped onto the bullet. The flaking or peeling can cause feeding/chambering problems.
If your lever action Marlin gives noticeably better ammo feeding with nickled cases versus brass cases, I'd suggest some judicious polishing and tuning of your rifle. This can done by any competent gunsmith, or by you if you go slowly and carefully. Try a websearch for "lever action rifle tuning".