It looks like I poked a bear with a stick here.
I say what I say because of observations of many rifles over many years.
4198 has been the culprit several times, as has the use of all the fillers mentioned.
Just because someone has done it for a long time with no problems proves nothing.
These rifles were made to shoot black - after all, it was the only propellant available.

This is all I can say.