The standard silver sample is 396 °, however, of the more than 10 examinations that I came across, they did not show Billon they showed a silver sample of ~ 750, here is one of them:
I also looked at many other coins with a standard silver sample of 396 °, but Billon was also not shown, everywhere the silver sample was from 710 to 970, here are some links:
https://numexpert.ru/wp-content/uploads/2019/05/1720557430.pdf
https://numexpert.ru/wp-content/uploads/2020/10/1720558002.pdf
https://numexpert.ru/wp-content/uploads/2018/10/1720557332.pdf