I've always used CCI #11 Magnum caps on my Black Diamond and System One. Never had an ignition problem with either loose Pyrodex powder or Pyrodex pellets. However, I do favor loose powder and have done alot more shooting with it than with pellets.

I noticed the Black Diamond was more accurate with #11 caps than with Musket caps and, since the #11sgot the job done, stopped using the Musket caps.
Bob