WHAT DOES BLACKHORN 209 POWDER IN STOCK MEAN?

I've a CVA optima in chrome steel. I even have the black horn 209 breech plug. I load a hundred grains by volume of Blackhorn 209 which has a 250 grain Barnes bullet. I have discovered that you truly should use a good primer. Don't use the primers created for black powder as this isn't black powder. I use the CCI magnum primers only. Never ever had