Yesterday I smoked my unlabeled Cellini Hungarian (20mmx52mm chamber)
and have the following advice:
About halfway down dump the ash from the top to allow more airflow (outside of bowl started to get hot and immediately cooled doing this);
About 2/3rds down tamp the ash lightly so tobacco continues to stay lit.
Doing these two things allowed me to keep tobacco lit from first light to bottom of bowl but it was a good 1.5 to 2 hour bowl while doing errands and driving.
just my 2 cents. Hungarian shape pipes like the Peterson pub pipe are my new favorite, easy smooth smokers. Something about the shape avoids a few problems with smaller bent pipes. Less bite, less heat, less gurgle, no tobacco up draft hole, cooler smoke.