In the photo above we have a Lyman brand, Universal Primer Flash Hole Deburring Tool
This is a “One Time Only” handloading task, once done you will never need to do it again until you change brass.
This tool reaches into the case to remove any factory imperfections on the inside of the primer flash hole. It can also be used on the outside to clean up that side too.
As a third and final use it can clear stainless steel wet tumbling media from the flash holes after running through the cleaning process.
This is a great little tool! The tool head will detach from the handle and you could put it in a drill if you chose to do so. I wouldn’t do it though, no need. I do detach the tool and use the handle for other tools though and I like that.
The black piece on the tool shaft is for alignment only, there is NO FUNCTION at all performed on the case mouth. There is also NO FUNCTION on the outside edges of the primer pocket, they are not touched.
This tool will clear and chamfer the flash hole inside & out if desired but nothing else.