You see this topic come up nearly every time somebody buys a new Rami (or any other CZ, no doubt), assumes it comes from the factory "clean," takes it out to the range and has jamming issues.
All CZs come from the factory (usually literally dripping) with packing grease / cosmoline. This is a preservative, not a lubricant. I prefer to field strip and submerge all the METAL parts in a bucket of good ol' Hoppes #9 for several hours or overnight to dissolve and clean out all the grease from all the nooks and crannies inside and outside (all wood or plastic parts, grips, etc. are removed prior to submersion). Also, keep all tritium / night sights above the surface of the solvent. Hoppes is good because, as well as easily dissolving the grease, it helps lubricate and prevent corrosion.
Then blow dry and lubricate with your favorite gun oil.