Immersion samplers for taking disc samples and pin samples, from heats of molten steel, alloys or other metal in basic oxygen furnaces, electric furnaces and open-hearth furnaces, are provided with slotted riser vent tubes serving to retard the escape of atmospheric air displaced by the inflowing molten metal entering the deeply immersed sampler while maintaining ample cross-sectional venting area despite accumulated droplets of spattered molten metal solidifying and blocking the vents. For use with melts of unkilled steel, apertured de-oxidizing retort portals are provided at the entrance end of the samplers with protective slag covers and vent apertures, creating a substantial de-oxidizing zone for the melt entering the sampler while releasing entrapped air during the sampler's immersion, and also allowing draining of the melt from the portal upon withdrawal of the immersed sampler from the furnace.