WHAT DOES BLACKHORN 209 POWDER IN STOCK MEAN?

I've a CVA optima in chrome steel. I also have the black horn 209 breech plug. I load a hundred grains by volume of Blackhorn 209 with a 250 grain Barnes bullet. I have found that you truly ought to use a superb primer. Don't use the primers produced for black powder as this is simply not black powder. I utilize the CCI magnum primers only. Hardly