Pro-Shot Chamber Lug and Recess Cleaning Tool

Pro-Shot Products lists this one for the chamber lug and recess. That is an area a straight bore brush passes right through without touching, so getting carbon out of it takes a tool shaped for the job.

Carbon collects in a recess faster than it does in a bore, because a recess is a corner rather than a straight path. Pro-Shot puts this one in its cleaning and gun care line, and the chamber lug and recess is the area it is listed for.