Thank ya'll for the comments and guidance. I "think" some of the looks of that puck are from the jury rigged setup I used for pressing. It didn't do very good at all and had a rough finish. I "think" most of the white is actually a light reflection while taking photo. I've got a batch milling now (started about 18 hrs ago) to try pressing with my new puck press setup. I'm hoping the puck will look better.
The sulfur (10 gram) and charcoal (15 gram)are both VERY fine (like talcum powder) out of the bag. The KNO3 (75 gram) is in pellets that I ran thru the pepper grinder, then ground in a mortar pestle type setup until it was "somewhat" fine. The dry mixture then went into the HF tumbler with lead balls and tumbled for around 20 hrs or so.
The puck is then dried at around 150F for a few hrs, then crumbled up and ran thru the pepper grinder.
When I get the milled powder from the tumbler today I'll take a photo of the powder and we'll see how fine the mixture is today.
Should I milled the KNO3 alone in the tumbler for a few hrs before mixing in the charcoal and sulfur? That might allow assuring the KNO3 is a finer powder?