1961MJS
Please allow me to elucidate
It "Depends." (No, not the kind in the plastic package)
Whether you get a Burnt Carbon Ring at the case mouth, will depend on the powder used. When, in my Sordid, Heathen, Ignorant past, I dabbled in that heathen fad smokeless stuff, I shot TightGroup in everything. I don't remember having a Carbon Ring with TightGroup.
Now that I am more educated, shooting BP and Subs, there is no Carbon Ring in the chambers of my guns. None. Zip. Nada. YMMV