Vetterli load that I use is Triple 7, 3F 55grs with a Lee 310 gr cast. Triple 7 doesn’t like to be compressed so the base of the bullet is seated touching the powder. Bullet is sized to 0.430. I couldn’t find regular black powder when I started reloading for the Swiss so I bought Triple 7. It worked good so I just stuck with it in those rifles even though I now have black powder for my other guns. I tried lighter bullets in them but accuracy wasn’t as good. I have two bolts changed to Center fire so I can swap them out and pick a rifle to shoot. I have 9 , various models.
Black powder is getting harder to find around here so any I find I have been buying. Hopefully rumours are true and a local company will be importing European powder within a few months.