This cartridge is a great example of two things:
- Pinfire cartridges had so many variations and even the sizes were not standardized at the very beginning. Jules Chaleyer marketed these as 8mm. He also marketed a 10mm and 12mm cartridge. This cartridge fits in the same guns as the later cartridges that standardized on the 7mm size.
- You can’t always believe everything you read that is published. I once wrote a whole article on these attributing them to Jullien & Gauthey based on previous publications that also identified them as such. I later found actual sources that contradicted the other publications. Original sources are always going to be better than anything you read online or in a book, especially if it’s not sourced.