Hornady 208 ammo

[MajorTom]

I went to the range today, and after firing a string of factory loaded Hornady 208 subs, I noticed a lot of hard yellow granules(almost seems like sand) in my chamber as well as on my bcg. I wiped down my bcg and chamber and fired some UMC supers(bore and bcg were clean of granules) and then some more Hornady 208's suppressed(a lot of granules on the bcg and in the receiver); I'm thinking that this unburned powder, but want to see what others have to say about it.
Before firing, I checked the rifle/loaded mags and didn't observe any granules.
Thoughts?

[300Blk]

Yes, unburned powder.