A plugging apparatus for plugging channels in a honeycomb structure used to form a particulate filter. The apparatus includes an extrusion apparatus that holds plugging material and that has an opening through which the plugging material is extruded. An extrusion plate having first through holes that correspond in location to a subset of honeycomb channels is arranged adjacent the opening. An annular flow plate is operatively arranged face-to-face with the extrusion plate. The annular flow plate has second through holes corresponding in location to the first through holes but that are smaller to compensate for a radial variation in the extrusion rate when plugging the channels in the honeycomb structure. The plugging apparatus is thus able to fill select channel ends with same-size plugs, which leads to a better-performing filter.