WHAT DOES BLACKHORN 209 POWDER IN STOCK MEAN?

I've a CVA optima in stainless steel. I also have the black horn 209 breech plug. I load 100 grains by quantity of Blackhorn 209 with a 250 grain Barnes bullet. I have discovered that you actually should use a very good primer. Will not utilize the primers made for black powder as this isn't black powder. I use the CCI magnum primers only. Never ex