These seem to be a popular topic at present, so perhaps the following (from my database) in one place may be useful (Updated 15Feb2022): The following primer markings are from all over the world. Some are known to have been used on European Sporting cartridges (note primers shown are NOT to...
" C (large) : Brazil, On CBC Magtech and other CBC cases "
Can't help with the powder. all I can tell you is it's stick powder.