If it's anything like the 10.4x38 Swiss, 10.4 x42, or 10.4 x 47 Italian I understand that 8mm Lebel brass is a better fit for the rim thickness. The .348 brass works for the Vetterli (and I get excellent accuracy) but the extractor will fall off the case if it isn't ejected briskly. The Lebel brass is supposed to be closer to the correct thickness. I have some Lebel brass but have not turned it into 10.4 Vetterli yet.
