WHAT DOES CCI SIZE 11 PERCUSSION CAPS MEAN?

I acquired a plain optima, not an elite, about six-7yrs in the past. I attempted a number of brands of primers in it. I could about 6 rounds through the normal CCIs or Acquire magnums after which you can the primers would get packed in with carbon. They were very difficult to extract! With most other makes 2-three photographs would call for equipme