WHAT DOES CCI 209 MAGNUM PRIMERS IN STOCK MEAN?

I acquired a plain optima, not an elite, about 6-7yrs in the past. I attempted a variety of manufacturers of primers in it. I could about six rounds through the standard CCIs or Win magnums and then the primers would get packed in with carbon. They were quite challenging to extract! With most other brands two-3 shots would have to have tools to acq